video: Prefer the window manager supplied coordinates for selecting a…

src/events/SDL_windowevents.c

@@ -69,6 +69,7 @@ bool SDL_SendWindowEvent(SDL_Window *window, SDL_EventType windowevent, int data
     case SDL_EVENT_WINDOW_MOVED:
         window->undefined_x = false;
         window->undefined_y = false;
+        window->use_pending_position_for_fullscreen = false;
         if (!(window->flags & SDL_WINDOW_FULLSCREEN)) {
             window->windowed.x = data1;
             window->windowed.y = data2;

src/video/SDL_sysvideo.h

@@ -96,9 +96,9 @@ struct SDL_Window
     SDL_Surface *surface;
     bool surface_valid;
 
-    bool is_repositioning; // Set during an SDL_SetWindowPosition() call.
     bool is_hiding;
     bool restore_on_show; // Child was hidden recursively by the parent, restore when shown.
+    bool use_pending_position_for_fullscreen;
     bool is_destroying;
     bool is_dropping; // drag/drop in progress, expecting SDL_SendDropComplete().
 

src/video/SDL_video.c

@@ -1660,20 +1660,21 @@ SDL_VideoDisplay *SDL_GetVideoDisplayForFullscreenWindow(SDL_Window *window)
         displayID = window->current_fullscreen_mode.displayID;
     }
 
-    /* The floating position is used here as a very common pattern is
-     * SDL_SetWindowPosition() followed by SDL_SetWindowFullscreen() to make the
-     * window fullscreen desktop on a specific display. If the backend doesn't
-     * support changing the window position, or the compositor hasn't yet actually
-     * moved the window, the current position won't be updated at the time of the
-     * fullscreen call.
+    /* This is used to handle the very common pattern of SDL_SetWindowPosition()
+     * followed immediately by SDL_SetWindowFullscreen() to make the window fullscreen
+     * desktop on a specific display. If the backend doesn't support changing the
+     * window position, or an async window manager hasn't yet actually moved the window,
+     * the current position won't be updated at the time of the fullscreen call.
      */
     if (!displayID) {
-        if (window->flags & SDL_WINDOW_FULLSCREEN && !window->is_repositioning) {
-            // This was a window manager initiated move, use the current position.
-            displayID = GetDisplayForRect(window->x, window->y, 1, 1);
-        } else {
+        if (window->use_pending_position_for_fullscreen) {
+            // The last coordinates were client requested; use the pending floating coordinates.
             displayID = GetDisplayForRect(window->floating.x, window->floating.y, window->floating.w, window->floating.h);
         }
+        else {
+            // The last coordinates were from the window manager; use the current position.
+            displayID = GetDisplayForRect(window->x, window->y, 1, 1);
+        }
     }
     if (!displayID) {
         // Use the primary display for a window if we can't find it anywhere else
@@ -2806,11 +2807,10 @@ bool SDL_SetWindowPosition(SDL_Window *window, int x, int y)
     window->floating.y = y;
     window->undefined_x = false;
     window->undefined_y = false;
+    window->use_pending_position_for_fullscreen = true;
 
     if (_this->SetWindowPosition) {
-        window->is_repositioning = true;
         const bool result = _this->SetWindowPosition(_this, window);
-        window->is_repositioning = false;
         if (result) {
             SDL_SyncIfRequired(window);
         }

src/video/wayland/SDL_waylandwindow.c

@@ -2651,6 +2651,7 @@ bool Wayland_SetWindowPosition(SDL_VideoDevice *_this, SDL_Window *window)
         RepositionPopup(window, false);
         return true;
     } else if (wind->shell_surface_type == WAYLAND_SHELL_SURFACE_TYPE_LIBDECOR || wind->shell_surface_type == WAYLAND_SHELL_SURFACE_TYPE_XDG_TOPLEVEL) {
+        const bool use_pending_position_for_fullscreen = window->use_pending_position_for_fullscreen;
         const int x = window->floating.x;
         const int y = window->floating.y;
 
@@ -2671,6 +2672,7 @@ bool Wayland_SetWindowPosition(SDL_VideoDevice *_this, SDL_Window *window)
          *
          * for positioning a desktop fullscreen window won't work without this.
          */
+        window->use_pending_position_for_fullscreen = use_pending_position_for_fullscreen;
         window->floating.x = x;
         window->floating.y = y;
 

src/video/x11/SDL_x11window.c

@@ -1060,7 +1060,17 @@ bool X11_SetWindowPosition(SDL_VideoDevice *_this, SDL_Window *window)
 {
     // Sync any pending fullscreen or maximize events.
     if (window->internal->pending_operation & (X11_PENDING_OP_FULLSCREEN | X11_PENDING_OP_MAXIMIZE)) {
+        // Save state in case it is overwritten while synchronizing.
+        const bool use_client_fs_coords = window->use_pending_position_for_fullscreen;
+        const int x = window->floating.x;
+        const int y = window->floating.y;
+
         X11_SyncWindow(_this, window);
+
+        // Restore state that may have been overwritten while synchronizing.
+        window->use_pending_position_for_fullscreen = use_client_fs_coords;
+        window->floating.x = x;
+        window->floating.y = y;
     }
 
     // Position will be set when window is de-maximized