Currently, the Control Panel button is placed in the same row like the group panel. This means that if you hide the group panel, but keep the Control Panel button, then you will end up with a single button an a considerable empty area on top of the GridView. This is noticeable mostly when you also display also the search panel. 

Add a property that allows you to move the position of the Control Panel button from the group panel's Grid row to the search panel's row. This way you can make the GridView more compact by placing the button in the search panel's area.