Refresh property grid when property is switched to read-only state.

Property grid is refreshed to reflect the new state of the property.

This is the backport of r76875.
See #16306.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_3_0_BRANCH@78514 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/propgrid/propgridiface.h

@@ -1077,6 +1077,14 @@ public:
             p->SetFlagRecursively(wxPG_PROP_READONLY, set);
         else
             p->ChangeFlag(wxPG_PROP_READONLY, set);
+
+        wxPropertyGridPageState* state = p->GetParentState();
+        if( state )
+        {
+            // If property is attached to the property grid
+            // then refresh the view.
+            RefreshProperty( p );
+        }
     }
 
     /** Sets property's value to unspecified.