Added a fix for X11 / Cinnamon window popups and maximize button not visible.

ptlinux/gamescope_runtime.py

@@ -291,13 +291,16 @@ def _tune_process_window(
         window = mapper.find_window_by_pid(process.pid)
         if window is not None:
             increments = resize_increments(width, height)
+            # Some X11 window managers keep the maximize decoration hidden until
+            # both the size constraints and allowed actions advertise resizing.
+            scaling_enabled = mapper.enable_window_scaling(window)
             increments_applied = mapper.set_resize_increments(
                 window,
                 (width, height),
                 increments,
             )
             compositing_preferred = mapper.prefer_composited_presentation(window)
-            if increments_applied and compositing_preferred:
+            if scaling_enabled and increments_applied and compositing_preferred:
                 return increments
         time.sleep(WINDOW_DISCOVERY_POLL_SECONDS)
     return None