Fix bug #13953 with spontaneous frame resizes on MS-Windows.

 src/w32term.c (w32_read_socket) <WM_WINDOWPOSCHANGED>: Remove old
 and incorrect code.  Treat WM_WINDOWPOSCHANGED like WM_ACTIVATE
 and WM_ACTIVATEAPP.
 (w32fullscreen_hook): If the frame is visible, reset
 f->want_fullscreen flag after changing the frame size.  If the
 frame is not visible, set f->want_fullscreen to FULLSCREEN_WAIT.

1 files changed, 12 insertions, 15 deletions

diff --git a/src/w32term.c b/src/w32term.c
index 680ad668ab3..6b51777839f 100644
--- a/src/w32term.c
+++ b/src/w32term.c
@@ -4705,26 +4705,20 @@ w32_read_socket (struct terminal *terminal,
           }
 
         case WM_WINDOWPOSCHANGED:
-          f = x_window_to_frame (dpyinfo, msg.msg.hwnd);
-          if (f)
-            {
-              if (f->want_fullscreen & FULLSCREEN_WAIT)
-                f->want_fullscreen &= ~(FULLSCREEN_WAIT|FULLSCREEN_BOTH);
-            }
-          check_visibility = 1;
-          break;
-
         case WM_ACTIVATE:
         case WM_ACTIVATEAPP:
           f = x_window_to_frame (dpyinfo, msg.msg.hwnd);
           if (f)
             {
-              /* If we are being activated, run the full-screen hook
-                 function, to actually install the required size in
-                 effect.  This is because when the hook is run from
-                 x_set_fullscreen, the frame might not yet be visible,
-                 if that call is a result of make-frame.  */
-              if (msg.msg.wParam)
+              /* Run the full-screen hook function also when we are
+                 being activated, to actually install the required
+                 size in effect, if the WAIT flag is set.  This is
+                 because when the hook is run from x_set_fullscreen,
+                 the frame might not yet be visible, if that call is a
+                 result of make-frame, and in that case the hook just
+                 sets the WAIT flag.  */
+              if ((msg.msg.message == WM_WINDOWPOSCHANGED || msg.msg.wParam)
+                  && (f->want_fullscreen & FULLSCREEN_WAIT))
                 w32fullscreen_hook (f);
               x_check_fullscreen (f);
             }
@@ -5739,8 +5733,11 @@ w32fullscreen_hook (FRAME_PTR f)
           x_set_window_size (f, 1, width, height);
           do_pending_window_change (0);
         }
+      f->want_fullscreen = FULLSCREEN_NONE;
       unblock_input ();
     }
+  else
+    f->want_fullscreen |= FULLSCREEN_WAIT;
 }
 
 /* Call this to change the size of frame F's x-window.