[gtk/matthiasc/surface-state-rework: 51/80] gtk/window: Only fake motion events on windows with pending allocations

[Matthias Clasen <matthiasc src gnome org>]

commit 3f7ebf256182f2bef0ac9651966563cc15b692ce
Author: Jonas Ådahl <jadahl gmail com>
Date:   Thu Dec 3 22:50:31 2020 +0100

    gtk/window: Only fake motion events on windows with pending allocations
    
    This fixes an issue where the focus of the window continuously received
    fake motion events even when a popover was open, making input events end
    up behind the popover.
    
    It also adds a comment describing why motion events are requested. Note
    that popovers won't work with this, and it's possible both in the past
    and now that sporadic missplaced motion events will appear, e.g. when a
    window changes allocation but a popover is open.

 gtk/gtkwindow.c | 32 ++++++++++++++++++++------------
 1 file changed, 20 insertions(+), 12 deletions(-)
---
diff --git a/gtk/gtkwindow.c b/gtk/gtkwindow.c
index 2ffc166894..07c23b0761 100644
--- a/gtk/gtkwindow.c
+++ b/gtk/gtkwindow.c
@@ -1894,7 +1894,6 @@ gtk_window_native_layout (GtkNative *native,
   GtkWindow *window = GTK_WINDOW (native);
   GtkWindowPrivate *priv = gtk_window_get_instance_private (window);
   GtkWidget *widget = GTK_WIDGET (native);
-  GdkSeat *seat;
 
   if (priv->surface_width != width || priv->surface_height != height)
     {
@@ -1903,21 +1902,30 @@ gtk_window_native_layout (GtkNative *native,
       priv->surface_height = height;
     }
 
-  seat = gdk_display_get_default_seat (gtk_widget_get_display (widget));
-  if (seat)
+  /* This fake motion event is needed for getting up to date pointer focus
+   * and coordinates when tho pointer didn't move but the layout changed
+   * within the window.
+   */
+  if (gtk_widget_needs_allocate (widget))
     {
-      GdkDevice *device;
-      GtkWidget *focus;
+      GdkSeat *seat;
 
-      device = gdk_seat_get_pointer (seat);
-      focus = gtk_window_lookup_pointer_focus_widget (GTK_WINDOW (widget),
-                                                      device, NULL);
-      if (focus)
+      seat = gdk_display_get_default_seat (gtk_widget_get_display (widget));
+      if (seat)
         {
-          GdkSurface *focus_surface =
-            gtk_native_get_surface (gtk_widget_get_native (focus));
+          GdkDevice *device;
+          GtkWidget *focus;
+
+          device = gdk_seat_get_pointer (seat);
+          focus = gtk_window_lookup_pointer_focus_widget (GTK_WINDOW (widget),
+                                                          device, NULL);
+          if (focus)
+            {
+              GdkSurface *focus_surface =
+                gtk_native_get_surface (gtk_widget_get_native (focus));
 
-          gdk_surface_request_motion (focus_surface);
+              gdk_surface_request_motion (focus_surface);
+            }
         }
     }