fix(window): skip unfocusable and hidden floats with "{count}<C-W>w" #33810

Problem: Using `<C-W>w`, `<C-W>W` or the ":wincmd" variants with a count can
enter unfocusable or hidden floating windows. This is especially problematic
when using the new in-development extui, which creates many unfocusable floats
for various UI elements.

Solution: Skip unfocusable and hidden floating windows. Instead, skip to the
next focusable, non-hidden window in the current tabpage's window list. Reword
the documentation a bit (hopefully an improvement?)

(cherry picked from commit 403fcacfc1)

runtime/doc/windows.txt

@@ -439,18 +439,17 @@ CTRL-W l	Move cursor to Nth window right of current one.  Uses the
 
 CTRL-W w					*CTRL-W_w* *CTRL-W_CTRL-W*
 CTRL-W CTRL-W	Without count: move cursor to the |focusable| window
-		below/right of the current one.  If there is no (focusable)
+		below/right of the current one.  If none, go to the top-left
-		window below or right, go to top-left window. With count: go
+		window.  With count: go to Nth window (numbered top-left to
-		to Nth window (windows are numbered from top-left to
+		bottom-right), skipping unfocusable windows.  To obtain the
-		bottom-right).  To obtain the window number see |bufwinnr()|
+		window number see |bufwinnr()| and |winnr()|.  When N is
-		and |winnr()|.  When N is larger than the number of windows go
+		larger than the number of windows go to the last focusable
-		to the last window.
+		window.
 
 						*CTRL-W_W*
 CTRL-W W	Without count: move cursor to the |focusable| window
-		above/left of current one.  If there is no window above or
+		above/left of current one.  If none, go to the bottom-right
-		left, go to bottom-right window.  With count: go to Nth
+		window.  With count: go to Nth window, like CTRL-W w.
-		window, like with CTRL-W w.
 
 CTRL-W t					*CTRL-W_t* *CTRL-W_CTRL-T*
 CTRL-W CTRL-T	Move cursor to top-left window.

src/nvim/window.c

@@ -347,12 +347,23 @@ newwindow:
     } else {
       win_T *wp;
       if (Prenum) {  // go to specified window
+        win_T *last_focusable = firstwin;
         for (wp = firstwin; --Prenum > 0;) {
+          if (!wp->w_floating || (!wp->w_config.hide && wp->w_config.focusable)) {
+            last_focusable = wp;
+          }
           if (wp->w_next == NULL) {
             break;
           }
           wp = wp->w_next;
         }
+        while (wp != NULL && wp->w_floating
+               && (wp->w_config.hide || !wp->w_config.focusable)) {
+          wp = wp->w_next;
+        }
+        if (wp == NULL) {  // went past the last focusable window
+          wp = last_focusable;
+        }
       } else {
         if (nchar == 'W') {  // go to previous window
           wp = curwin->w_prev;

test/functional/ui/float_spec.lua

@@ -5632,6 +5632,59 @@ describe('float window', function()
                                                     |
           ]])
         end
+
+        api.nvim_open_win(
+          0,
+          false,
+          { relative = "editor", width = 1, height = 1, row = 0, col = 0 }
+        )
+        api.nvim_open_win(
+          0,
+          false,
+          { relative = "editor", width = 1, height = 1, row = 0, col = 0, focusable = false }
+        )
+        api.nvim_open_win(
+          0,
+          false,
+          { relative = "editor", width = 1, height = 1, row = 0, col = 0, focusable = false }
+        )
+        api.nvim_open_win(
+          0,
+          false,
+          { relative = "editor", width = 1, height = 1, row = 0, col = 0, focusable = true }
+        )
+        api.nvim_open_win(
+          0,
+          false,
+          { relative = "editor", width = 1, height = 1, row = 0, col = 0, focusable = false }
+        )
+        local nr_focusable = {}
+        for nr = 1, fn.winnr("$") do
+          table.insert(nr_focusable, api.nvim_win_get_config(fn.win_getid(nr)).focusable)
+        end
+        eq({true, false, true, false, false, true, false}, nr_focusable)
+
+        command("1wincmd w")
+        eq(1, fn.winnr())
+        command("2wincmd w")
+        eq(3, fn.winnr())
+        command("3wincmd w")
+        eq(3, fn.winnr())
+        command("4wincmd w")
+        eq(6, fn.winnr())
+        command("5wincmd w")
+        eq(6, fn.winnr())
+        command("6wincmd w")
+        eq(6, fn.winnr())
+        command("7wincmd w")
+        eq(6, fn.winnr())
+
+        feed("1<c-w>w")
+        eq(1, fn.winnr())
+        feed("2<c-w>w")
+        eq(3, fn.winnr())
+        feed("999<c-w>w")
+        eq(6, fn.winnr())
       end)
 
       it("W", function()