WM_GETDLGCODE top-level constant
Sent to the window procedure associated with a control. By default, the system handles all keyboard input to the control; the system interprets certain types of keyboard input as dialog box navigation keys. To override this default behavior, the control can respond to the WM_GETDLGCODE message to indicate the types of input it wants to process itself.
const WM_GETDLGCODE = 0x0087;