Number of action buttons on the action bar

When I add action buttons with .AddMenuItem or .AddMenuItem2 up to 5 are displayed on the action bar. With 6 action buttons the action overflow button and only 4 action buttons are displayed on the action bar with the other 2 in the action overflow menu. My question is how can I control how many action buttons are on the action bar? For example I want only 2 action buttons on the action bar and 6 in the action overflow menu.

Thank you