This macro sets the enable state of the item in the dialog template to the enable flag.

#define INCL_WINWINDOWMGR /* Or use INCL_WIN, INCL_PM, */
#include <os2.h>

HWND      hwndDlg;  /*  Dialog window handle. */
USHORT    usId;     /*  Identity of the item in the dialog template (button id). */
BOOL      fEnable;  /*  Enable flag. */
BOOL      rc;       /*  Success indicator. */

rc = WinEnableControl(hwndDlg, usId, fEnable);