The TCM_SETPADDING message sets the amount of space (padding) around each tab's icon and label in a tab control. You can send this message explicitly or by using the TabCtrl_SetPadding macro.
TCM_SETPADDING
wParam = 0; // not used; must be zero
lParam = MAKELPARAM(cx, cy); // amount of horizontal and vertical padding, in pixels
Parameters
cx and cy
Amount of horizontal and vertical padding, in pixels.
Return Values
No return value.
See Also