My issue was different. The problem was it required more clint area while drop down. case CBN_DROPDOWN: { RECT rcClient; // Get the coordinates of the parent window's client area. GetClientRect((HWND) lParam, &rcClient); MoveWindow((HWND)lParam,rcClient.left,rcClient.top ,rcClient.right,rcClient.bottom+300,true); } I added this above code. which fixed my issue.
birajendu SonicWALL Bangalore India