Fixes a bug:
When there is a widget without siblings and its geometry manager is set to 'grid', changing it to 'pack' or 'place', it will still show the grid row/col in the object treeview.
This pull request will clear the grid row/col from the object treeview (for that widget) when the geometry manager changes from grid to pack or grid, when the widget doesn't have any siblings.
Fixes a bug: When there is a widget without siblings and its geometry manager is set to 'grid', changing it to 'pack' or 'place', it will still show the grid row/col in the object treeview.
This pull request will clear the grid row/col from the object treeview (for that widget) when the geometry manager changes from grid to pack or grid, when the widget doesn't have any siblings.
Example: