Overwrites an attribute for a menu that was created by #PanelMenuManager.
This can be useful when you want to update an attribute such as "accel" when an accelerator has changed due to user mappings.
the menu that was retreived with panel.menu_manager.MenuManager.getMenuById
the index of the item in the menu
the attribute to change
the new value for the attribute
Overwrites an attribute for a menu that was created by #PanelMenuManager.
This can be useful when you want to update an attribute such as "accel" when an accelerator has changed due to user mappings.