TCM_ADJUSTRECT message

Calculates a tab control's display area given a window rectangle, or calculates the window rectangle that would correspond to a specified display area. You can send this message explicitly or by using the TabCtrl_AdjustRect macro.

wParam

Operation to perform. If this parameter is TRUE, lParam specifies a display rectangle and receives the corresponding window rectangle. If this parameter is FALSE, lParam specifies a window rectangle and receives the corresponding display area.

lParam

Pointer to a RECT structure that specifies the given rectangle and receives the calculated rectangle.

No return value.

This message applies only to tab controls that are at the top. It does not apply to tab controls that are on the sides or bottom.