If the EnableFilterControlPopupMenuScrolling property is set to true, scroll buttons are displayed within popup menus that do not fit onto the page, allowing end-users to scroll through menu items.
The image below shows a Prefilter window with a popup menu invoked, and the EnableFilterControlPopupMenuScrolling option enabled.

If the EnableFilterControlPopupMenuScrolling property is set to false, popup menus are trimmed if they cannot be displayed in their entirety.
You can also specify whether the pivot grid context menus can be scrolled. To do this, use the EnableContextMenuScrolling property.