reduce layout

Author: willmcgugan

src/textual/screen.py

@@ -1368,7 +1368,7 @@ async def _on_layout(self, message: messages.Layout) -> None:
                 break
             widget = ancestor
 
-        if layout_required:
+        if layout_required and not self._layout_required:
             self._layout_required = True
             self.check_idle()