API Frame SetClampedToScreen

Prevents a from moving off-screen. Frame:SetClampedToScreen(clamped)

Arguments

 * clamped : - True to enable clamping, false to permit moving off-screen.

Details

 * defines padding within/beyond the screen edges.
 * Overrides placement by any of the following:
 * Any calls to
 * User dragging after
 * User resizing after

Example
Despite calling SetPoint toward 100 pixels beyond the left screen edge, the SpellBookFrame remains fully visible on the screen: