# Function Reference

# _WinAPI_DwmDefWindowProc

Default window procedure for Desktop Window Manager (DWM) hit testing within the non-client area

#include <WinAPIGdi.au3>
_WinAPI_DwmDefWindowProc ( $hWnd, $iMsg, $wParam, $lParam )

## Parameters

$hWnd | A handle to the window procedure that received the message.
$iMsg | The message.
$wParam | Additional message-specific information. The content of this parameter depends on the message.
$lParam | Additional message-specific information. The content of this parameter depends on the message.

## Return Value

Success: | The result of the hit test.
Failure: | 0 and sets the @error flag to non-zero.

## Remarks

When creating custom frames that include the standard caption buttons, WM_NCHITTEST and other non-client hit test messages should first be passed to _WinAPI_DwmDefWindowProc().
This enables the DWM to provide hit testing for the captions buttons.
If _WinAPI_DwmDefWindowProc() does not handle the non-client hit test messages, further processing of these messages might be neccessary.
This function requires Windows Vista or later.

## See Also

Search DwmDefWindowProc in MSDN Library.