#8394 Destroy the palette when the invoker is dettached

src/sugar/graphics/palette.py

@@ -749,6 +749,9 @@ class Invoker(gobject.GObject):
 
     def detach(self):
         self.parent = None
+        if self._palette is not None:
+            self._palette.destroy()
+            self._palette = None
 
     def _get_position_for_alignment(self, alignment, palette_dim):
         palette_halign = alignment[0]