An application sends the CB_GETHORIZONTALEXTENT message to retrieve from a combo box the width, in pixels, by which the list box can be scrolled horizontally (the scrollable width). This is applicable only if the list box has a horizontal scroll bar.
CB_GETHORIZONTALEXTENT
wParam = 0; // not used, must be zero
lParam = 0; // not used, must be zero
This message has no parameters.
The return value is the scrollable width, in pixels.
Windows NT: Requires version 4.0 or later.
Windows: Requires Windows 95 or later.
Windows CE: Requires version 1.0 or later.
Header: Declared in winuser.h.
Combo Boxes Overview, Combo Box Messages, CB_SETHORIZONTALEXTENT