wayland: Fix SDL_SetWindowSize() being dropped right after exiting fullscreen

If we get a SDL_SetWindowSize() call right after SDL_SetWindowFullscreen() but
before we've gotten a new configure event from the compositor, the attempt to
set our window size will silently fail (when libdecor is enabled).

Fix this by remembering that we need to commit a new size, so we can do that
in decoration_frame_configure().

src/video/wayland/SDL_waylandwindow.c

@@ -414,9 +414,10 @@ decoration_frame_configure(struct libdecor_frame *frame,
         if (window->flags & SDL_WINDOW_ALLOW_HIGHDPI) {
             scale_factor = driverdata->scale_factor;
         }
-    } else if (!(window->flags & SDL_WINDOW_RESIZABLE)) {
+    } else if (!(window->flags & SDL_WINDOW_RESIZABLE) || (floating && wind->floating_resize_pending)) {
         width = window->windowed.w;
         height = window->windowed.h;
+        wind->floating_resize_pending = SDL_FALSE;
     } else {
         /* This will never set 0 for width/height unless the function returns false */
         if (!libdecor_configuration_get_content_size(configuration, frame, &width, &height)) {
@@ -1424,6 +1425,8 @@ void Wayland_SetWindowSize(_THIS, SDL_Window * window)
     if (data->shell.libdecor &&
         wind->shell_surface.libdecor.frame &&
         !libdecor_frame_is_floating(wind->shell_surface.libdecor.frame)) {
+            /* Commit the resize when we re-enter floating state */
+            wind->floating_resize_pending = SDL_TRUE;
             return;
     }
 #endif

src/video/wayland/SDL_waylandwindow.h

@@ -87,6 +87,7 @@ typedef struct {
 
     float scale_factor;
     SDL_bool needs_resize_event;
+    SDL_bool floating_resize_pending;
 } SDL_WindowData;
 
 extern void Wayland_ShowWindow(_THIS, SDL_Window *window);