Fix invisible mouse pointers on Windows.

* src/w32fns.c: Include windowsx.h.
(w32_wnd_proc): If the mouse moved and the mouse pointer is
invisible, make it visible again even when the main (Lisp)
thread is busy.
* src/w32term.c (w32_toggle_invisible_pointer): Rather then
garbaging the frame have the input thread call SetCursor.

2 files changed, 27 insertions, 12 deletions

diff --git a/src/w32fns.c b/src/w32fns.c
index 180d326bc98..836dc10118d 100644
--- a/src/w32fns.c
+++ b/src/w32fns.c
@@ -73,6 +73,7 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 
 #include <dlgs.h>
 #include <imm.h>
+#include <windowsx.h>
 
 #include "font.h"
 #include "w32font.h"
@@ -3493,13 +3494,31 @@ w32_wnd_proc (HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
       return (msg == WM_XBUTTONDOWN || msg == WM_XBUTTONUP);
 
     case WM_MOUSEMOVE:
-      /* Ignore mouse movements as long as the menu is active.  These
-         movements are processed by the window manager anyway, and
-         it's wrong to handle them as if they happened on the
-         underlying frame.  */
       f = x_window_to_frame (dpyinfo, hwnd);
-      if (f && f->output_data.w32->menubar_active)
-        return 0;
+      if (f)
+        {
+          /* Ignore mouse movements as long as the menu is active.
+             These movements are processed by the window manager
+             anyway, and it's wrong to handle them as if they happened
+             on the underlying frame.  */
+          if (f->output_data.w32->menubar_active)
+            return 0;
+
+          /* If the mouse moved, and the mouse pointer is invisible,
+             make it visible again.  We do this here so as to be able
+             to show the mouse pointer even when the main
+             (a.k.a. "Lisp") thread is busy doing something.  */
+          static int last_x, last_y;
+          int x = GET_X_LPARAM (lParam);
+          int y = GET_Y_LPARAM (lParam);
+
+          if (f->pointer_invisible
+              && (x != last_x || y != last_y))
+            f->pointer_invisible = false;
+
+          last_x = x;
+          last_y = y;
+        }
 
       /* If the mouse has just moved into the frame, start tracking
          it, so we will be notified when it leaves the frame.  Mouse
diff --git a/src/w32term.c b/src/w32term.c
index 7c5f2db3a4c..fbd31b15de2 100644
--- a/src/w32term.c
+++ b/src/w32term.c
@@ -6613,14 +6613,10 @@ w32_toggle_invisible_pointer (struct frame *f, bool invisible)
   if (f->pointer_invisible != invisible)
     {
       f->pointer_invisible = invisible;
-      SET_FRAME_GARBAGED (f);
+      w32_define_cursor (FRAME_W32_WINDOW (f),
+                         f->output_data.w32->current_cursor);
     }
 
-  if (invisible)
-    SetCursor (NULL);
-  else
-    SetCursor (f->output_data.w32->current_cursor);
-
   unblock_input ();
 }