feat(ui): support grid=0 in nvim_input_mouse #32535

Problem: Multigrid UIs have to find out which window to send the input by using the Nvim focus rules, which are not fully documented. Furthermore,`getmousepos()` has several problems when multigrid is enabled, with the main one being that screenrow and screencol are window relative instead of screen relative, due to the fact that the UI don't send any absolute coordinates. Solution: Allow passing 0 as grid to `nvim_input_mouse`, with absolute coordinates, which lets nvim determine the actual window to send the mouse input to. This works as long as nvim is in charge of the window positioning. If the UI repositions or resizes the windows, it can still pass the grid it determines like before.
2025-09-14 23:38:17 +00:00 · 2025-09-14 00:57:04 +03:00
parent c1648cf820
commit 8ae9a44d38
15 changed files with 2388 additions and 2162 deletions
--- a/runtime/doc/api.txt
+++ b/runtime/doc/api.txt
@@ -1147,8 +1147,9 @@ nvim_input_mouse({button}, {action}, {modifier}, {grid}, {row}, {col})
                    press, except that the "-" separator is optional, so
                    "C-A-", "c-a" and "CA" can all be used to specify
                    Ctrl+Alt+click.
-      • {grid}      (`integer`) Grid number if the client uses |ui-multigrid|,
-                    else 0.
+      • {grid}      (`integer`) Grid number (used by |ui-multigrid| client),
+                    or 0 to let Nvim decide positioning of windows. For more
+                    information, see |dev-ui-multigrid|
      • {row}       (`integer`) Mouse row-position (zero-based, like redraw
                    events)
      • {col}       (`integer`) Mouse column-position (zero-based, like redraw
--- a/runtime/doc/develop.txt
+++ b/runtime/doc/develop.txt
@@ -685,5 +685,23 @@ External UIs are expected to implement these common features:
 - Handle the "restart" UI event so that |:restart| works.
 - Detect capslock and show an indicator if capslock is active.

+Multigrid UI ~
+                                                        *dev-ui-multigrid*
+- A multigrid UI should display floating windows using one of the following
+  methods, using the `win_float_pos` |ui-multigrid| event. Different methods
+  can be selected for each window as needed.
+
+  1. Let Nvim determine the position and z-order of the windows. This can be
+  achieved by using the `compindex`, `screen_row`, and `screen_col` information from
+  the `win_float_pos` UI event. To allow Nvim to automatically determine the grid,
+  the UI should call `nvim_input_mouse` with 0 as the `grid` parameter.
+  2. Use the `anchor`, `anchor_grid`, `anchor_row`, `anchor_col`, and `zindex` as
+  references for positioning the windows. If windows are outside the screen,
+  it is the UI's responsibility to reposition and/or resize them. Since Nvim
+  lacks information about actual window placement in this case, the UI must
+  call `nvim_input_mouse` with the actual grid id, factoring in `mouse_enabled`.
+  Note: Some API functions may return unexpected results for these windows due
+  to the missing information.
+- For external windows, the grid id should also be passed to `nvim_input_mouse`.

 vim:tw=78:ts=8:sw=4:et:ft=help:norl:
--- a/runtime/doc/news.txt
+++ b/runtime/doc/news.txt
@@ -339,6 +339,7 @@ UI
  • "Error executing Lua:" changed to "Lua:".
 • 'busy' status is shown in default statusline with symbol ◐
 • Improved LSP signature help rendering.
+• Multigrid UIs can call nvim_input_mouse with grid 0 to let Nvim decide the grid.

 VIMSCRIPT

--- a/runtime/lua/vim/_meta/api.lua
+++ b/runtime/lua/vim/_meta/api.lua
@@ -1606,7 +1606,8 @@ function vim.api.nvim_input(keys) end
 --- The same specifiers are used as for a key press, except
 --- that the "-" separator is optional, so "C-A-", "c-a"
 --- and "CA" can all be used to specify Ctrl+Alt+click.
--- @param grid integer Grid number if the client uses `ui-multigrid`, else 0.
+--- @param grid integer Grid number (used by `ui-multigrid` client), or 0 to let Nvim decide positioning of
+--- windows. For more information, see [dev-ui-multigrid]
 --- @param row integer Mouse row-position (zero-based, like redraw events)
 --- @param col integer Mouse column-position (zero-based, like redraw events)
 function vim.api.nvim_input_mouse(button, action, modifier, grid, row, col) end
--- a/src/nvim/api/vim.c
+++ b/src/nvim/api/vim.c
@@ -382,7 +382,8 @@ Integer nvim_input(uint64_t channel_id, String keys)
 ///                 The same specifiers are used as for a key press, except
 ///                 that the "-" separator is optional, so "C-A-", "c-a"
 ///                 and "CA" can all be used to specify Ctrl+Alt+click.
-/// @param grid Grid number if the client uses |ui-multigrid|, else 0.
+/// @param grid Grid number (used by |ui-multigrid| client), or 0 to let Nvim decide positioning of
+///             windows. For more information, see [dev-ui-multigrid]
 /// @param row Mouse row-position (zero-based, like redraw events)
 /// @param col Mouse column-position (zero-based, like redraw events)
 /// @param[out] err Error details, if any
--- a/src/nvim/getchar.c
+++ b/src/nvim/getchar.c
@@ -2013,7 +2013,7 @@ static void getchar_common(typval_T *argvars, typval_T *rettv, bool allow_number
        int winnr = 1;
        // Find the window at the mouse coordinates and compute the
        // text position.
-        win_T *const win = mouse_find_win(&grid, &row, &col);
+        win_T *const win = mouse_find_win_inner(&grid, &row, &col);
        if (win == NULL) {
          return;
        }
--- a/src/nvim/mouse.c
+++ b/src/nvim/mouse.c
@@ -235,7 +235,7 @@ static int get_fpos_of_mouse(pos_T *mpos)
  }

  // find the window where the row is in
-  win_T *wp = mouse_find_win(&grid, &row, &col);
+  win_T *wp = mouse_find_win_inner(&grid, &row, &col);
  if (wp == NULL) {
    return IN_UNKNOWN;
  }
@@ -663,7 +663,7 @@ bool do_mouse(oparg_T *oap, int c, int dir, int count, bool fixindent)
    int click_grid = mouse_grid;
    int click_row = mouse_row;
    int click_col = mouse_col;
-    win_T *wp = mouse_find_win(&click_grid, &click_row, &click_col);
+    win_T *wp = mouse_find_win_inner(&click_grid, &click_row, &click_col);
    if (wp == NULL) {
      return false;
    }
@@ -1093,7 +1093,7 @@ void ins_mousescroll(int dir)
    int grid = mouse_grid;
    int row = mouse_row;
    int col = mouse_col;
-    curwin = mouse_find_win(&grid, &row, &col);
+    curwin = mouse_find_win_inner(&grid, &row, &col);
    if (curwin == NULL) {
      curwin = old_curwin;
      return;
@@ -1263,8 +1263,8 @@ retnomove:
  }

  // find the window where the row is in and adjust "row" and "col" to be
-  // relative to top-left of the window
-  win_T *wp = mouse_find_win(&grid, &row, &col);
+  // relative to top-left of the window inner area
+  win_T *wp = mouse_find_win_inner(&grid, &row, &col);
  if (wp == NULL) {
    return IN_UNKNOWN;
  }
@@ -1581,7 +1581,7 @@ void nv_mousescroll(cmdarg_T *cap)
    int grid = mouse_grid;
    int row = mouse_row;
    int col = mouse_col;
-    curwin = mouse_find_win(&grid, &row, &col);
+    curwin = mouse_find_win_inner(&grid, &row, &col);
    if (curwin == NULL) {
      curwin = old_curwin;
      return;
@@ -1695,10 +1695,10 @@ bool mouse_comp_pos(win_T *win, int *rowp, int *colp, linenr_T *lnump)
 }

 /// Find the window at "grid" position "*rowp" and "*colp".  The positions are
-/// updated to become relative to the top-left of the window.
+/// updated to become relative to the top-left of the window inner area.
 ///
 /// @return NULL when something is wrong.
-win_T *mouse_find_win(int *gridp, int *rowp, int *colp)
+win_T *mouse_find_win_inner(int *gridp, int *rowp, int *colp)
 {
  win_T *wp_grid = mouse_find_grid_win(gridp, rowp, colp);
  if (wp_grid) {
@@ -1740,6 +1740,20 @@ win_T *mouse_find_win(int *gridp, int *rowp, int *colp)
  return NULL;
 }

+/// Find the window at "grid" position "*rowp" and "*colp".  The positions are
+/// updated to become relative to the top-left of the window.
+///
+/// @return NULL when something is wrong.
+win_T *mouse_find_win_outer(int *gridp, int *rowp, int *colp)
+{
+  win_T *wp = mouse_find_win_inner(gridp, rowp, colp);
+  if (wp) {
+    *rowp += wp->w_winrow_off;
+    *colp += wp->w_wincol_off;
+  }
+  return wp;
+}
+
 static win_T *mouse_find_grid_win(int *gridp, int *rowp, int *colp)
 {
  if (*gridp == msg_grid.handle) {
@@ -1755,18 +1769,26 @@ static win_T *mouse_find_grid_win(int *gridp, int *rowp, int *colp)
    }
  } else if (*gridp == 0) {
    ScreenGrid *grid = ui_comp_mouse_focus(*rowp, *colp);
-    FOR_ALL_WINDOWS_IN_TAB(wp, curtab) {
-      if (&wp->w_grid_alloc != grid) {
-        continue;
-      }
+    if (grid == &pum_grid) {
      *gridp = grid->handle;
-      *rowp -= grid->comp_row + wp->w_grid.row_offset;
-      *colp -= grid->comp_col + wp->w_grid.col_offset;
-      return wp;
+      *rowp -= grid->comp_row;
+      *colp -= grid->comp_col;
+      // The popup menu doesn't have a window, so return NULL
+      return NULL;
+    } else {
+      FOR_ALL_WINDOWS_IN_TAB(wp, curtab) {
+        if (&wp->w_grid_alloc != grid) {
+          continue;
+        }
+        *gridp = grid->handle;
+        *rowp -= wp->w_winrow + wp->w_grid.row_offset;
+        *colp -= wp->w_wincol + wp->w_grid.col_offset;
+        return wp;
+      }
    }

-    // no float found, click on the default grid
-    // TODO(bfredl): grid can be &pum_grid, allow select pum items by mouse?
+    // No grid found, return the default grid. With multigrid this happens for split separators for
+    // example.
    *gridp = DEFAULT_GRID_HANDLE;
  }
  return NULL;
@@ -1877,7 +1899,7 @@ static void mouse_check_grid(colnr_T *vcolp, int *flagsp)
  int click_col = mouse_col;

  // XXX: this doesn't change click_grid if it is 1, even with multigrid
-  if (mouse_find_win(&click_grid, &click_row, &click_col) != curwin
+  if (mouse_find_win_inner(&click_grid, &click_row, &click_col) != curwin
      // Only use vcols[] after the window was redrawn.  Mainly matters
      // for tests, a user would not click before redrawing.
      || curwin->w_redr_type != 0) {
@@ -1931,7 +1953,7 @@ void f_getmousepos(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
  tv_dict_add_nr(d, S_LEN("screenrow"), (varnumber_T)mouse_row + 1);
  tv_dict_add_nr(d, S_LEN("screencol"), (varnumber_T)mouse_col + 1);

-  win_T *wp = mouse_find_win(&grid, &row, &col);
+  win_T *wp = mouse_find_win_inner(&grid, &row, &col);
  if (wp != NULL) {
    int height = wp->w_height + wp->w_hsep_height + wp->w_status_height;
    // The height is adjusted by 1 when there is a bottom border. This is not
--- a/src/nvim/popupmenu.c
+++ b/src/nvim/popupmenu.c
@@ -37,6 +37,7 @@
 #include "nvim/memory_defs.h"
 #include "nvim/menu.h"
 #include "nvim/message.h"
+#include "nvim/mouse.h"
 #include "nvim/move.h"
 #include "nvim/option.h"
 #include "nvim/option_defs.h"
@@ -1325,6 +1326,10 @@ static void pum_position_at_mouse(int min_width)
  int col = mouse_col;
  pum_win_row_offset = 0;
  pum_win_col_offset = 0;
+
+  if (ui_has(kUIMultigrid) && grid == 0) {
+    mouse_find_win_outer(&grid, &row, &col);
+  }
  if (grid > 1) {
    win_T *wp = get_win_by_grid_handle(grid);
    if (wp != NULL) {
@@ -1395,17 +1400,27 @@ static void pum_position_at_mouse(int min_width)
 /// Select the pum entry at the mouse position.
 static void pum_select_mouse_pos(void)
 {
-  if (mouse_grid == pum_grid.handle) {
-    pum_selected = mouse_row;
+  int grid = mouse_grid;
+  int row = mouse_row;
+  int col = mouse_col;
+
+  if (grid == 0) {
+    mouse_find_win_outer(&grid, &row, &col);
+  }
+
+  if (grid == pum_grid.handle) {
+    pum_selected = row;
    return;
-  } else if (mouse_grid != pum_anchor_grid
-             || mouse_col < pum_left_col - pum_win_col_offset
-             || mouse_col >= pum_right_col - pum_win_col_offset) {
+  }
+
+  if (grid != pum_anchor_grid
+      || col < pum_left_col - pum_win_col_offset
+      || col >= pum_right_col - pum_win_col_offset) {
    pum_selected = -1;
    return;
  }

-  int idx = mouse_row - (pum_row - pum_win_row_offset);
+  int idx = row - (pum_row - pum_win_row_offset);

  if (idx < 0 || idx >= pum_height) {
    pum_selected = -1;
--- a/src/nvim/terminal.c
+++ b/src/nvim/terminal.c
@@ -1907,7 +1907,7 @@ static bool send_mouse_event(Terminal *term, int c)
  int row = mouse_row;
  int col = mouse_col;
  int grid = mouse_grid;
-  win_T *mouse_win = mouse_find_win(&grid, &row, &col);
+  win_T *mouse_win = mouse_find_win_inner(&grid, &row, &col);
  if (mouse_win == NULL) {
    goto end;
  }
--- a/src/nvim/ui_compositor.c
+++ b/src/nvim/ui_compositor.c
@@ -318,6 +318,15 @@ ScreenGrid *ui_comp_mouse_focus(int row, int col)
      return grid;
    }
  }
+  if (ui_has(kUIMultigrid)) {
+    FOR_ALL_WINDOWS_IN_TAB(wp, curtab) {
+      ScreenGrid *grid = &wp->w_grid_alloc;
+      if (grid->mouse_enabled && row >= wp->w_winrow && row < wp->w_winrow + grid->rows
+          && col >= wp->w_wincol && col < wp->w_wincol + grid->cols) {
+        return grid;
+      }
+    }
+  }
  return NULL;
 }

--- a/src/nvim/window.c
+++ b/src/nvim/window.c
@@ -5187,6 +5187,8 @@ win_T *win_alloc(win_T *after, bool hidden)
  new_wp->handle = ++last_win_id;
  pmap_put(int)(&window_handles, new_wp->handle, new_wp);

+  new_wp->w_grid_alloc.mouse_enabled = true;
+
  grid_assign_handle(&new_wp->w_grid_alloc);

  // Init w: variables.
--- a/src/nvim/winfloat.c
+++ b/src/nvim/winfloat.c
@@ -192,7 +192,7 @@ void win_config_float(win_T *wp, WinConfig fconfig)
    int row = mouse_row;
    int col = mouse_col;
    int grid = mouse_grid;
-    win_T *mouse_win = mouse_find_win(&grid, &row, &col);
+    win_T *mouse_win = mouse_find_win_inner(&grid, &row, &col);
    if (mouse_win != NULL) {
      fconfig.relative = kFloatRelativeWindow;
      fconfig.row += row;
--- a/test/functional/ui/float_spec.lua
+++ b/test/functional/ui/float_spec.lua
@@ -971,7 +971,7 @@ describe('float window', function()
    api.nvim_win_set_config(win, api.nvim_win_get_config(win))
  end)

-  local function with_ext_multigrid(multigrid)
+  local function with_ext_multigrid(multigrid, send_mouse_grid)
    local screen, attrs
    before_each(function()
      screen = Screen.new(40, 7, { ext_multigrid = multigrid })
@@ -6164,8 +6164,12 @@ describe('float window', function()
      end)

      local function test_float_mouse_focus()
-        if multigrid then
+        if send_mouse_grid then
          api.nvim_input_mouse('left', 'press', '', 4, 0, 0)
+        else
+          api.nvim_input_mouse('left', 'press', '', 0, 2, 5)
+        end
+        if multigrid then
          screen:expect {
            grid = [[
          ## grid 1
@@ -6183,7 +6187,6 @@ describe('float window', function()
            float_pos = expected_pos,
          }
        else
-          api.nvim_input_mouse('left', 'press', '', 0, 2, 5)
          screen:expect([[
            x                                       |
            {0:~                                       }|
@@ -6194,8 +6197,12 @@ describe('float window', function()
          ]])
        end

-        if multigrid then
+        if send_mouse_grid then
          api.nvim_input_mouse('left', 'press', '', 2, 0, 0)
+        else
+          api.nvim_input_mouse('left', 'press', '', 0, 0, 0)
+        end
+        if multigrid then
          screen:expect {
            grid = [[
          ## grid 1
@@ -6213,7 +6220,6 @@ describe('float window', function()
            float_pos = expected_pos,
          }
        else
-          api.nvim_input_mouse('left', 'press', '', 0, 0, 0)
          screen:expect([[
            ^x                                       |
            {0:~                                       }|
@@ -6237,27 +6243,53 @@ describe('float window', function()
      local function test_float_mouse_no_focus()
        api.nvim_buf_set_lines(0, -1, -1, true, { 'a' })
        expected_pos[4][6] = false
-        if multigrid then
+        if send_mouse_grid then
          api.nvim_input_mouse('left', 'press', '', 4, 0, 0)
-          screen:expect {
-            grid = [[
-          ## grid 1
-            [2:----------------------------------------]|*6
-            [3:----------------------------------------]|
-          ## grid 2
-            ^x                                       |
-            a                                       |
-            {0:~                                       }|*4
-          ## grid 3
-                                                    |
-          ## grid 4
-            {1:y                   }|
-            {2:~                   }|
-          ]],
-            float_pos = expected_pos,
-          }
        else
          api.nvim_input_mouse('left', 'press', '', 0, 2, 5)
+        end
+        if multigrid then
+          if send_mouse_grid then
+            -- Sending input to grid 4 is a user error, you are not supposed to pass a grid
+            -- that isn't focusable. In this case, nothing happens and the input is not passed
+            -- through to grid 4, like normally happens when you pass grid 0.
+            screen:expect {
+              grid = [[
+            ## grid 1
+              [2:----------------------------------------]|*6
+              [3:----------------------------------------]|
+            ## grid 2
+              ^x                                       |
+              a                                       |
+              {0:~                                       }|*4
+            ## grid 3
+                                                      |
+            ## grid 4
+              {1:y                   }|
+              {2:~                   }|
+            ]],
+              float_pos = expected_pos,
+            }
+          else
+            screen:expect {
+              grid = [[
+            ## grid 1
+              [2:----------------------------------------]|*6
+              [3:----------------------------------------]|
+            ## grid 2
+              x                                       |
+              ^a                                       |
+              {0:~                                       }|*4
+            ## grid 3
+                                                      |
+            ## grid 4
+              {1:y                   }|
+              {2:~                   }|
+            ]],
+              float_pos = expected_pos,
+            }
+          end
+        else
          screen:expect([[
            x                                       |
            ^a                                       |
@@ -6268,8 +6300,12 @@ describe('float window', function()
          ]])
        end

-        if multigrid then
+        if send_mouse_grid then
          api.nvim_input_mouse('left', 'press', '', 2, 0, 0)
+        else
+          api.nvim_input_mouse('left', 'press', '', 0, 0, 0)
+        end
+        if multigrid then
          screen:expect {
            grid = [[
          ## grid 1
@@ -6289,7 +6325,6 @@ describe('float window', function()
            unchanged = true,
          }
        else
-          api.nvim_input_mouse('left', 'press', '', 0, 0, 0)
          screen:expect([[
            ^x                                       |
            a                                       |
@@ -7959,7 +7994,11 @@ describe('float window', function()
          },
        }

-        api.nvim_input_mouse('left', 'press', '', 4, 0, 0)
+        if send_mouse_grid then
+          api.nvim_input_mouse('left', 'press', '', 4, 0, 0)
+        else
+          api.nvim_input_mouse('left', 'press', '', 0, 2, 5)
+        end
        screen:expect {
          grid = [[
        ## grid 1
@@ -7982,7 +8021,11 @@ describe('float window', function()
          },
        }

-        api.nvim_input_mouse('left', 'drag', '', 4, 1, 2)
+        if send_mouse_grid then
+          api.nvim_input_mouse('left', 'drag', '', 4, 1, 2)
+        else
+          api.nvim_input_mouse('left', 'drag', '', 0, 3, 7)
+        end
        screen:expect {
          grid = [[
        ## grid 1
@@ -8074,7 +8117,11 @@ describe('float window', function()
          },
        }

-        api.nvim_input_mouse('left', 'press', '', 4, 1, 1)
+        if send_mouse_grid then
+          api.nvim_input_mouse('left', 'press', '', 4, 1, 1)
+        else
+          api.nvim_input_mouse('left', 'press', '', 0, 1, 6)
+        end
        screen:expect {
          grid = [[
        ## grid 1
@@ -8099,7 +8146,11 @@ describe('float window', function()
          },
        }

-        api.nvim_input_mouse('left', 'drag', '', 4, 2, 3)
+        if send_mouse_grid then
+          api.nvim_input_mouse('left', 'drag', '', 4, 2, 3)
+        else
+          api.nvim_input_mouse('left', 'drag', '', 0, 2, 8)
+        end
        screen:expect {
          grid = [[
        ## grid 1
@@ -8193,7 +8244,11 @@ describe('float window', function()
          },
        }

-        api.nvim_input_mouse('left', 'press', '', 4, 1, 0)
+        if send_mouse_grid then
+          api.nvim_input_mouse('left', 'press', '', 4, 1, 0)
+        else
+          api.nvim_input_mouse('left', 'press', '', 0, 2, 5)
+        end
        screen:expect {
          grid = [[
        ## grid 1
@@ -8217,7 +8272,11 @@ describe('float window', function()
          },
        }

-        api.nvim_input_mouse('left', 'drag', '', 4, 2, 2)
+        if send_mouse_grid then
+          api.nvim_input_mouse('left', 'drag', '', 4, 2, 2)
+        else
+          api.nvim_input_mouse('left', 'drag', '', 0, 3, 7)
+        end
        screen:expect {
          grid = [[
        ## grid 1
@@ -8304,7 +8363,11 @@ describe('float window', function()
          {0:~                   }|*2
        ]])

-        api.nvim_input_mouse('left', 'press', '', 4, 2, 2)
+        if send_mouse_grid then
+          api.nvim_input_mouse('left', 'press', '', 4, 2, 2)
+        else
+          api.nvim_input_mouse('left', 'press', '', 0, 2, 22)
+        end
        screen:expect([[
        ## grid 1
          [2:-------------------]{5:│}[4:--------------------]|*5
@@ -8322,7 +8385,11 @@ describe('float window', function()
          {0:~                   }|*2
        ]])

-        api.nvim_input_mouse('left', 'drag', '', 4, 1, 1)
+        if send_mouse_grid then
+          api.nvim_input_mouse('left', 'drag', '', 4, 1, 1)
+        else
+          api.nvim_input_mouse('left', 'drag', '', 0, 1, 21)
+        end
        screen:expect([[
        ## grid 1
          [2:-------------------]{5:│}[4:--------------------]|*5
@@ -8409,21 +8476,21 @@ describe('float window', function()
        }
      end

-      if multigrid then
+      if send_mouse_grid then
        api.nvim_input_mouse('left', 'press', '', 4, 3, 1)
      else
        api.nvim_input_mouse('left', 'press', '', 0, 3, 6)
      end
      eq({ 0, 3, 1, 0, 1 }, fn.getcurpos())

-      if multigrid then
+      if send_mouse_grid then
        api.nvim_input_mouse('left', 'press', '', 4, 3, 2)
      else
        api.nvim_input_mouse('left', 'press', '', 0, 3, 7)
      end
      eq({ 0, 3, 1, 0, 2 }, fn.getcurpos())

-      if multigrid then
+      if send_mouse_grid then
        api.nvim_input_mouse('left', 'press', '', 4, 3, 10)
      else
        api.nvim_input_mouse('left', 'press', '', 0, 3, 15)
@@ -8470,8 +8537,12 @@ describe('float window', function()
        }
      end

-      if multigrid then
+      if send_mouse_grid then
        api.nvim_input_mouse('left', 'press', '', 4, 2, 1)
+      else
+        api.nvim_input_mouse('left', 'press', '', 0, 2, 6)
+      end
+      if multigrid then
        screen:expect {
          grid = [[
        ## grid 1
@@ -8496,7 +8567,6 @@ describe('float window', function()
          },
        }
      else
-        api.nvim_input_mouse('left', 'press', '', 0, 2, 6)
        screen:expect {
          grid = [[
               {5:┌────────────────────┐}             |
@@ -8510,21 +8580,21 @@ describe('float window', function()
        }
      end

-      if multigrid then
+      if send_mouse_grid then
        api.nvim_input_mouse('left', 'press', '', 4, 2, 2)
      else
        api.nvim_input_mouse('left', 'press', '', 0, 2, 7)
      end
      eq({ 0, 2, 1, 0, 1 }, fn.getcurpos())

-      if multigrid then
+      if send_mouse_grid then
        api.nvim_input_mouse('left', 'press', '', 4, 2, 3)
      else
        api.nvim_input_mouse('left', 'press', '', 0, 2, 8)
      end
      eq({ 0, 2, 1, 0, 2 }, fn.getcurpos())

-      if multigrid then
+      if send_mouse_grid then
        api.nvim_input_mouse('left', 'press', '', 4, 2, 11)
      else
        api.nvim_input_mouse('left', 'press', '', 0, 2, 16)
@@ -8840,8 +8910,12 @@ describe('float window', function()
      end

      -- Test scrolling by mouse
-      if multigrid then
+      if send_mouse_grid then
        api.nvim_input_mouse('wheel', 'down', '', 4, 2, 2)
+      else
+        api.nvim_input_mouse('wheel', 'down', '', 0, 4, 7)
+      end
+      if multigrid then
        screen:expect {
          grid = [[
        ## grid 1
@@ -8865,7 +8939,6 @@ describe('float window', function()
          float_pos = { [4] = { 1001, 'NW', 1, 2, 5, true, 50, 1, 2, 5 } },
        }
      else
-        api.nvim_input_mouse('wheel', 'down', '', 0, 4, 7)
        screen:expect([[
          Ut enim ad minim veniam, quis nostrud             |
          exercitation ullamco laboris nisi ut aliquip ex   |
@@ -11047,10 +11120,15 @@ describe('float window', function()
    end)
  end

-  describe('with ext_multigrid', function()
-    with_ext_multigrid(true)
+  describe('with ext_multigrid and actual mouse grid', function()
+    with_ext_multigrid(true, true)
  end)
+
+  describe('with ext_multigrid and mouse grid 0', function()
+    with_ext_multigrid(true, false)
+  end)
+
  describe('without ext_multigrid', function()
-    with_ext_multigrid(false)
+    with_ext_multigrid(false, false)
  end)
 end)
--- a/test/functional/ui/mouse_spec.lua
+++ b/test/functional/ui/mouse_spec.lua
--- a/test/functional/ui/popupmenu_spec.lua
+++ b/test/functional/ui/popupmenu_spec.lua
@@ -1018,7 +1018,7 @@ end)
 describe('builtin popupmenu', function()
  before_each(clear)

-  local function with_ext_multigrid(multigrid)
+  local function with_ext_multigrid(multigrid, send_mouse_grid)
    local screen
    before_each(function()
      screen = Screen.new(32, 20, { ext_multigrid = multigrid })
@@ -2553,8 +2553,12 @@ describe('builtin popupmenu', function()
        ]])
      end

-      if multigrid then
+      if send_mouse_grid then
        api.nvim_input_mouse('wheel', 'down', '', 2, 9, 33)
+      else
+        api.nvim_input_mouse('wheel', 'down', '', 0, 9, 40)
+      end
+      if multigrid then
        screen:expect({
          grid = [[
          ## grid 1
@@ -2595,7 +2599,6 @@ describe('builtin popupmenu', function()
          float_pos = { [5] = { -1, 'NW', 4, 1, 3, false, 100, 1, 1, 3 } },
        })
      else
-        api.nvim_input_mouse('wheel', 'down', '', 0, 9, 40)
        screen:expect([[
          Est ^                                                        |
            L{n: sunt           }{12: }sit amet, consectetur                   |
@@ -2672,8 +2675,12 @@ describe('builtin popupmenu', function()
        ]])
      end

-      if multigrid then
+      if send_mouse_grid then
        api.nvim_input_mouse('wheel', 'up', '', 2, 9, 33)
+      else
+        api.nvim_input_mouse('wheel', 'up', '', 0, 9, 40)
+      end
+      if multigrid then
        screen:expect({
          grid = [[
          ## grid 1
@@ -2712,7 +2719,6 @@ describe('builtin popupmenu', function()
          float_pos = { [5] = { -1, 'NW', 4, 1, 3, false, 100, 1, 1, 3 } },
        })
      else
-        api.nvim_input_mouse('wheel', 'up', '', 0, 9, 40)
        screen:expect([[
          Est e^                                                       |
            L{n: elit           } sit amet, consectetur                   |
@@ -2781,8 +2787,12 @@ describe('builtin popupmenu', function()
        ]])
      end

-      if multigrid then
+      if send_mouse_grid then
        api.nvim_input_mouse('wheel', 'down', '', 2, 9, 33)
+      else
+        api.nvim_input_mouse('wheel', 'down', '', 0, 9, 40)
+      end
+      if multigrid then
        screen:expect({
          grid = [[
          ## grid 1
@@ -2813,7 +2823,6 @@ describe('builtin popupmenu', function()
          float_pos = { [5] = { -1, 'NW', 4, 1, 3, false, 100, 1, 1, 3 } },
        })
      else
-        api.nvim_input_mouse('wheel', 'down', '', 0, 9, 40)
        screen:expect([[
          Est es^                                                      |
            L{n: esse           } sit amet, consectetur                   |
@@ -2948,8 +2957,12 @@ describe('builtin popupmenu', function()
        ]])
      end

-      if multigrid then
+      if send_mouse_grid then
        api.nvim_input_mouse('wheel', 'down', '', 2, 9, 33)
+      else
+        api.nvim_input_mouse('wheel', 'down', '', 0, 9, 40)
+      end
+      if multigrid then
        screen:expect({
          grid = [[
          ## grid 1
@@ -2988,7 +3001,6 @@ describe('builtin popupmenu', function()
          float_pos = { [5] = { -1, 'NW', 4, 1, 3, false, 100, 1, 1, 3 } },
        })
      else
-        api.nvim_input_mouse('wheel', 'down', '', 0, 9, 40)
        screen:expect([[
          Est eu^                                                      |
            L{n: elit           } sit amet, consectetur                   |
@@ -6614,9 +6626,13 @@ describe('builtin popupmenu', function()
        return new_state
      end

-      local no_sel_screen ---@type string|test.functional.ui.screen.Expect
-      if multigrid then
+      local no_sel_screen ---@type string|test.function.ui.screen.Expect
+      if send_mouse_grid then
        api.nvim_input_mouse('right', 'press', '', 2, 0, 4)
+      else
+        feed('<RightMouse><4,0>')
+      end
+      if multigrid then
        no_sel_screen = {
          grid = [[
        ## grid 1
@@ -6635,7 +6651,6 @@ describe('builtin popupmenu', function()
          float_pos = { [4] = { -1, 'NW', 2, 1, 3, false, 250, 2, 1, 3 } },
        }
      else
-        feed('<RightMouse><4,0>')
        no_sel_screen = [[
          ^popup menu test                 |
          {1:~  }{n: foo }{1:                        }|
@@ -6673,8 +6688,12 @@ describe('builtin popupmenu', function()
      screen:expect(no_menu_screen)
      eq('bar', api.nvim_get_var('menustr'))

-      if multigrid then
+      if send_mouse_grid then
        api.nvim_input_mouse('right', 'press', '', 2, 2, 20)
+      else
+        feed('<RightMouse><20,2>')
+      end
+      if multigrid then
        screen:expect({
          grid = [[
        ## grid 1
@@ -6693,7 +6712,6 @@ describe('builtin popupmenu', function()
          float_pos = { [4] = { -1, 'NW', 2, 3, 19, false, 250, 2, 3, 19 } },
        })
      else
-        feed('<RightMouse><20,2>')
        screen:expect([[
          ^popup menu test                 |
          {1:~                               }|*2
@@ -6702,8 +6720,12 @@ describe('builtin popupmenu', function()
          :let g:menustr = 'b{n: baz }        |
        ]])
      end
-      if multigrid then
+      if send_mouse_grid then
        api.nvim_input_mouse('right', 'press', '', 2, 0, 18)
+      else
+        feed('<RightMouse><18,0>')
+      end
+      if multigrid then
        screen:expect({
          grid = [[
        ## grid 1
@@ -6722,7 +6744,6 @@ describe('builtin popupmenu', function()
          float_pos = { [4] = { -1, 'NW', 2, 1, 17, false, 250, 2, 1, 17 } },
        })
      else
-        feed('<RightMouse><18,0>')
        screen:expect([[
          ^popup menu test                 |
          {1:~                }{n: foo }{1:          }|
@@ -6732,8 +6753,12 @@ describe('builtin popupmenu', function()
          :let g:menustr = 'bar'          |
        ]])
      end
-      if multigrid then
+      if send_mouse_grid then
        api.nvim_input_mouse('right', 'press', '', 4, 1, 3)
+      else
+        feed('<RightMouse><20,2>')
+      end
+      if multigrid then
        screen:expect({
          grid = [[
        ## grid 1
@@ -6752,7 +6777,6 @@ describe('builtin popupmenu', function()
          float_pos = { [4] = { -1, 'NW', 2, 3, 19, false, 250, 2, 3, 19 } },
        })
      else
-        feed('<RightMouse><20,2>')
        screen:expect([[
          ^popup menu test                 |
          {1:~                               }|*2
@@ -6761,7 +6785,7 @@ describe('builtin popupmenu', function()
          :let g:menustr = 'b{n: baz }        |
        ]])
      end
-      if multigrid then
+      if send_mouse_grid then
        api.nvim_input_mouse('left', 'press', '', 4, 2, 2)
      else
        feed('<LeftMouse><21,5>')
@@ -6770,8 +6794,12 @@ describe('builtin popupmenu', function()
      screen:expect(no_menu_screen)
      eq('baz', api.nvim_get_var('menustr'))

-      if multigrid then
+      if send_mouse_grid then
        api.nvim_input_mouse('right', 'press', '', 2, 0, 4)
+      else
+        feed('<RightMouse><4,0>')
+      end
+      if multigrid then
        no_sel_screen = {
          grid = [[
        ## grid 1
@@ -6790,7 +6818,6 @@ describe('builtin popupmenu', function()
          float_pos = { [4] = { -1, 'NW', 2, 1, 3, false, 250, 2, 1, 3 } },
        }
      else
-        feed('<RightMouse><4,0>')
        no_sel_screen = [[
          ^popup menu test                 |
          {1:~  }{n: foo }{1:                        }|
@@ -6801,13 +6828,13 @@ describe('builtin popupmenu', function()
        ]]
      end
      screen:expect(no_sel_screen)
-      if multigrid then
+      if send_mouse_grid then
        api.nvim_input_mouse('right', 'drag', '', 2, 3, 6)
      else
        feed('<RightDrag><6,3>')
      end
      screen:expect(screen_replace(no_sel_screen, '{n: baz }', '{12: baz }'))
-      if multigrid then
+      if send_mouse_grid then
        api.nvim_input_mouse('right', 'release', '', 2, 1, 6)
      else
        feed('<RightRelease><6,1>')
@@ -6818,35 +6845,36 @@ describe('builtin popupmenu', function()
      no_sel_screen = screen_replace(no_sel_screen, [['baz']], [['foo']])

      eq(false, screen.options.mousemoveevent)
-      if multigrid then
+
+      if send_mouse_grid then
        api.nvim_input_mouse('right', 'press', '', 2, 0, 4)
      else
        feed('<RightMouse><4,0>')
      end
      screen:expect(no_sel_screen)
      eq(true, screen.options.mousemoveevent)
-      if multigrid then
+      if send_mouse_grid then
        api.nvim_input_mouse('wheel', 'up', '', 2, 0, 4)
      else
        feed('<ScrollWheelUp><4,0>')
      end
      screen:expect(screen_replace(no_sel_screen, '{n: foo }', '{12: foo }'))
      eq(true, screen.options.mousemoveevent)
-      if multigrid then
+      if send_mouse_grid then
        api.nvim_input_mouse('move', '', '', 4, 2, 3)
      else
        feed('<MouseMove><6,3>')
      end
      screen:expect(screen_replace(no_sel_screen, '{n: baz }', '{12: baz }'))
      eq(true, screen.options.mousemoveevent)
-      if multigrid then
+      if send_mouse_grid then
        api.nvim_input_mouse('wheel', 'down', '', 4, 2, 3)
      else
        feed('<ScrollWheelDown><6,3>')
      end
      screen:expect(screen_replace(no_sel_screen, '{n: bar }', '{12: bar }'))
      eq(true, screen.options.mousemoveevent)
-      if multigrid then
+      if send_mouse_grid then
        api.nvim_input_mouse('left', 'press', '', 4, 1, 3)
      else
        feed('<LeftMouse><6,2>')
@@ -6857,8 +6885,12 @@ describe('builtin popupmenu', function()
      eq('bar', api.nvim_get_var('menustr'))

      command('set laststatus=0 | botright split')
-      if multigrid then
+      if send_mouse_grid then
        api.nvim_input_mouse('right', 'press', '', 5, 1, 20)
+      else
+        feed('<RightMouse><20,4>')
+      end
+      if multigrid then
        screen:expect({
          grid = [[
        ## grid 1
@@ -6882,7 +6914,6 @@ describe('builtin popupmenu', function()
          float_pos = { [4] = { -1, 'SW', 5, 1, 19, false, 250, 2, 1, 19 } },
        })
      else
-        feed('<RightMouse><20,4>')
        screen:expect([[
          popup menu test                 |
          {1:~                  }{n: foo }{1:        }|
@@ -6892,8 +6923,12 @@ describe('builtin popupmenu', function()
          :let g:menustr = 'bar'          |
        ]])
      end
-      if multigrid then
+      if send_mouse_grid then
        api.nvim_input_mouse('left', 'press', '', 4, 2, 2)
+      else
+        feed('<LeftMouse><21,3>')
+      end
+      if multigrid then
        screen:expect([[
        ## grid 1
          [2:--------------------------------]|*2
@@ -6910,7 +6945,6 @@ describe('builtin popupmenu', function()
          {1:~                               }|
        ]])
      else
-        feed('<LeftMouse><21,3>')
        screen:expect([[
          popup menu test                 |
          {1:~                               }|
@@ -6923,8 +6957,12 @@ describe('builtin popupmenu', function()
      eq('baz', api.nvim_get_var('menustr'))

      command('set winwidth=1 | rightbelow vsplit')
-      if multigrid then
+      if send_mouse_grid then
        api.nvim_input_mouse('right', 'press', '', 6, 1, 14)
+      else
+        feed('<RightMouse><30,4>')
+      end
+      if multigrid then
        screen:expect({
          grid = [[
        ## grid 1
@@ -6951,7 +6989,6 @@ describe('builtin popupmenu', function()
          float_pos = { [4] = { -1, 'SW', 6, 1, 12, false, 250, 2, 1, 28 } },
        })
      else
-        feed('<RightMouse><30,4>')
        screen:expect([[
          popup menu test                 |
          {1:~                           }{n: foo}|
@@ -6961,8 +6998,12 @@ describe('builtin popupmenu', function()
          :let g:menustr = 'baz'          |
        ]])
      end
-      if multigrid then
+      if send_mouse_grid then
        api.nvim_input_mouse('left', 'press', '', 4, 0, 2)
+      else
+        feed('<LeftMouse><31,1>')
+      end
+      if multigrid then
        screen:expect([[
        ## grid 1
          [2:--------------------------------]|*2
@@ -6982,7 +7023,6 @@ describe('builtin popupmenu', function()
          {1:~               }|
        ]])
      else
-        feed('<LeftMouse><31,1>')
        screen:expect([[
          popup menu test                 |
          {1:~                               }|
@@ -6995,8 +7035,12 @@ describe('builtin popupmenu', function()
      eq('foo', api.nvim_get_var('menustr'))

      command('setlocal winbar=WINBAR')
-      if multigrid then
+      if send_mouse_grid then
        api.nvim_input_mouse('right', 'press', '', 6, 1, 14)
+      else
+        feed('<RightMouse><30,4>')
+      end
+      if multigrid then
        no_sel_screen = {
          grid = [[
        ## grid 1
@@ -7023,7 +7067,6 @@ describe('builtin popupmenu', function()
          float_pos = { [4] = { -1, 'SW', 6, 1, 12, false, 250, 2, 1, 28 } },
        }
      else
-        feed('<RightMouse><30,4>')
        no_sel_screen = [[
          popup menu test                 |
          {1:~                           }{n: foo}|
@@ -7034,20 +7077,24 @@ describe('builtin popupmenu', function()
        ]]
      end
      screen:expect(no_sel_screen)
-      if multigrid then
+      if send_mouse_grid then
        api.nvim_input_mouse('right', 'drag', '', 6, 0, 15)
      else
        feed('<RightDrag><31,3>')
      end
      screen:expect(screen_replace(no_sel_screen, '{n: baz}', '{12: baz}'))
-      if multigrid then
+      if send_mouse_grid then
        api.nvim_input_mouse('right', 'release', '', 6, 1, 15)
      else
        feed('<RightRelease><31,4>')
      end
      screen:expect(no_sel_screen)
-      if multigrid then
+      if send_mouse_grid then
        api.nvim_input_mouse('left', 'press', '', 4, 1, 2)
+      else
+        feed('<LeftMouse><31,2>')
+      end
+      if multigrid then
        screen:expect([[
        ## grid 1
          [2:--------------------------------]|*2
@@ -7067,7 +7114,6 @@ describe('builtin popupmenu', function()
          ^popup menu test |
        ]])
      else
-        feed('<LeftMouse><31,2>')
        screen:expect([[
          popup menu test                 |
          {1:~                               }|
@@ -7181,7 +7227,7 @@ describe('builtin popupmenu', function()
        { 0, 5, 19 },
        { 0, 5, 18 },
      }
-      if multigrid then
+      if send_mouse_grid then
        for i = 1, 7 do
          local _, row, col = unpack(pos[i])
          pos[i] = { 2, row - 2, col - 5 }
@@ -7206,7 +7252,7 @@ describe('builtin popupmenu', function()
      screen:expect(no_menu_screen)
      eq('', api.nvim_get_var('menustr'))

-      if multigrid then
+      if send_mouse_grid then
        for i = 2, 6, 2 do
          local _, row, col = unpack(pos[i])
          pos[i] = { 4, row - 1, col - 14 }
@@ -7329,7 +7375,7 @@ describe('builtin popupmenu', function()
        { 0, 5, 21 },
        { 0, 5, 22 },
      }
-      if multigrid then
+      if send_mouse_grid then
        for i = 1, 7 do
          local _, row, col = unpack(pos[i])
          pos[i] = { 2, row - 2, col - 5 }
@@ -7352,7 +7398,7 @@ describe('builtin popupmenu', function()
      screen:expect(no_menu_screen)
      eq('', api.nvim_get_var('menustr'))

-      if multigrid then
+      if send_mouse_grid then
        for i = 2, 6, 2 do
          local _, row, col = unpack(pos[i])
          pos[i] = { 4, row - 1, col - 12 }
@@ -7551,8 +7597,12 @@ describe('builtin popupmenu', function()
        call setline(1, join(range(20)))
      ]])

-      if multigrid then
+      if send_mouse_grid then
        api.nvim_input_mouse('right', 'press', '', 2, 0, 45 - 1)
+      else
+        api.nvim_input_mouse('right', 'press', '', 0, 0, 45 - 1)
+      end
+      if multigrid then
        screen:expect({
          grid = [[
          ## grid 1
@@ -7578,7 +7628,6 @@ describe('builtin popupmenu', function()
          float_pos = { [4] = { -1, 'NW', 2, 1, 33, false, 250, 2, 1, 33 } },
        })
      else
-        api.nvim_input_mouse('right', 'press', '', 0, 0, 45 - 1)
        screen:expect([[
          0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 ^18 19 |
          {1:~                                }{n: Undo            }|
@@ -7598,8 +7647,12 @@ describe('builtin popupmenu', function()
      feed('<Esc>')

      command('set rightleft')
-      if multigrid then
+      if send_mouse_grid then
        api.nvim_input_mouse('right', 'press', '', 2, 0, 50 - 45)
+      else
+        api.nvim_input_mouse('right', 'press', '', 0, 0, 50 - 45)
+      end
+      if multigrid then
        screen:expect({
          grid = [[
          ## grid 1
@@ -7625,7 +7678,6 @@ describe('builtin popupmenu', function()
          float_pos = { [4] = { -1, 'NW', 2, 1, 0, false, 250, 2, 1, 0 } },
        })
      else
-        api.nvim_input_mouse('right', 'press', '', 0, 0, 50 - 45)
        screen:expect([[
           91 8^1 71 61 51 41 31 21 11 01 9 8 7 6 5 4 3 2 1 0|
          {n:            odnU }{1:                                ~}|
@@ -8678,11 +8730,15 @@ describe('builtin popupmenu', function()
    end
  end

-  describe('with ext_multigrid', function()
-    with_ext_multigrid(true)
+  describe('with ext_multigrid and actual mouse grid', function()
+    with_ext_multigrid(true, true)
+  end)
+
+  describe('with ext_multigrid and mouse grid 0', function()
+    with_ext_multigrid(true, false)
  end)

  describe('without ext_multigrid', function()
-    with_ext_multigrid(false)
+    with_ext_multigrid(false, false)
  end)
 end)