This example shows how to check if WinOpenWindowDC has been called for this window.

#define INCL_WINHOOKS
#define INCL_WINTHUNKAPI
#include <OS2.H>
HWND  hwndClient;           /* window handle. */

if(WinQueryWindowModel(hwndClient) == PM_MODEL_2X)
{
     /*  The 32-bit memory model of the 80386 processor.    */
}