Draft: Update checked state of grid button when switching the grid

The checked state of the grid button was not updated when the grid was only displayed during Draft commands.

src/Mod/Draft/draftguitools/gui_trackers.py

@@ -43,6 +43,7 @@ import FreeCADGui
 import Draft
 import DraftVecUtils
 from FreeCAD import Vector
+from draftutils import grid_observer
 from draftutils import gui_utils
 from draftutils import params
 from draftutils import utils
@@ -1350,6 +1351,16 @@ class gridTracker(Tracker):
         self.setAxesColor(wp)
         self.on()
 
+    def on(self):
+        """Set the visibility to True and update the checked state grid button."""
+        super().on()
+        grid_observer._update_grid_gui()
+
+    def off(self):
+        """Set the visibility to False and update the checked state grid button."""
+        super().off()
+        grid_observer._update_grid_gui()
+
     def getClosestNode(self, point):
         """Return the closest node from the given point."""
         wp = self._get_wp()