While it is possible to modify colors to get a desired look, common code is often used to display FRAME controls, whether on a TAB control or not. When common code is used, the FRAME controls on a TAB look different from FRAME controls not on a TAB, especially in the background color of the FRAME title.
Setting this variable to TRUE (ON, YES, 1) causes all FRAME controls to paint as if they are on a TAB control, particularly in the colors used to draw the control. If set to FALSE (OFF, NO, 0), then the FRAME controls on a TAB continue to have a different look than FRAME controls not on a TAB.