vim-patch:8.0.1138: click in window toolbar starts Visual mode

Problem:    Click in window toolbar starts Visual mode.
Solution:   Add the MOUSE_WINBAR flag.
eb163d73b1

src/nvim/mouse.c

@@ -60,6 +60,7 @@ int jump_to_mouse(int flags,
 {
   static int on_status_line = 0;        // #lines below bottom of window
   static int on_sep_line = 0;           // on separator right of window
+  static bool in_winbar = false;
   static int prev_row = -1;
   static int prev_col = -1;
   static win_T *dragwin = NULL;         // window being dragged
@@ -139,8 +140,10 @@ retnomove:
       // A click in the window toolbar does not enter another window or
       // change Visual highlighting.
       winbar_click(wp, col);
-      return IN_OTHER_WIN;
+      in_winbar = true;
+      return IN_OTHER_WIN | MOUSE_WINBAR;
     }
+    in_winbar = false;
 
     // winpos and height may change in win_enter()!
     if (grid == DEFAULT_GRID_HANDLE && row >= wp->w_height) {
@@ -231,6 +234,9 @@ retnomove:
       did_drag |= count;
     }
     return IN_SEP_LINE;                         // Cursor didn't move
+  } else if (in_winbar) {
+    // After a click on the window toolbar don't start Visual mode.
+    return IN_OTHER_WIN | MOUSE_WINBAR;
   } else {
     // keep_window_focus must be true
     // before moving the cursor for a left click, stop Visual mode

src/nvim/mouse.h

@@ -16,6 +16,7 @@
 #define CURSOR_MOVED           0x100
 #define MOUSE_FOLD_CLOSE       0x200   // clicked on '-' in fold column
 #define MOUSE_FOLD_OPEN        0x400   // clicked on '+' in fold column
+#define MOUSE_WINBAR           0x800   // in window toolbar
 
 // flags for jump_to_mouse()
 #define MOUSE_FOCUS            0x01    // need to stay in this window

src/nvim/normal.c

@@ -2559,7 +2559,14 @@ do_mouse (
    * JUMP!
    */
   jump_flags = jump_to_mouse(jump_flags,
-      oap == NULL ? NULL : &(oap->inclusive), which_button);
+                             oap == NULL ? NULL : &(oap->inclusive),
+                             which_button);
+
+  // A click in the window toolbar has no side effects.
+  if (jump_flags & MOUSE_WINBAR) {
+    return false;
+  }
+
   moved = (jump_flags & CURSOR_MOVED);
   in_status_line = (jump_flags & IN_STATUS_LINE);
   in_sep_line = (jump_flags & IN_SEP_LINE);