DwmExtendFrameIntoClientArea function (dwmapi.h)

Extends the window frame into the client area.

Syntax

HRESULT DwmExtendFrameIntoClientArea(
 [in] HWND hWnd,
 [in] const MARGINS *pMarInset
);

Parameters

[in] hWnd

The handle to the window in which the frame will be extended into the client area.

[in] pMarInset

A pointer to a MARGINS structure that describes the margins to use when extending the frame into the client area.

Return value

If this function succeeds, it returns S_OK. Otherwise, it returns an HRESULT error code.

Remarks

This function must be called whenever Desktop Window Manager (DWM) composition is toggled. Handle the WM_DWMCOMPOSITIONCHANGED message for composition change notification.

Use negative margin values to create the "sheet of glass" effect where the client area is rendered as a solid surface with no window border.

Examples

The following sample demonstrates how to extend the bottom margin, creating a large bottom frame.

HRESULT ExtendIntoClientBottom(HWND hwnd)
{
 // Set margins, extending the bottom margin
 MARGINS margins = {0,0,0,25};
 HRESULT hr = S_OK;

 // Extend frame on the bottom of client area
 hr = DwmExtendFrameIntoClientArea(hwnd,&margins);
 if (SUCCEEDED(hr))
 {
 // ...
 }
 return hr;
}

The following sample demonstrates the "sheet of glass" effect where the client area is rendered without a window border.

HRESULT ExtendIntoClientAll(HWND hwnd)
{
 // Negative margins have special meaning to DwmExtendFrameIntoClientArea.
 // Negative margins create the "sheet of glass" effect, where the client area
 // is rendered as a solid surface with no window border.
 MARGINS margins = {-1};
 HRESULT hr = S_OK;

 // Extend the frame across the entire window.
 hr = DwmExtendFrameIntoClientArea(hwnd,&margins);
 if (SUCCEEDED(hr))
 {
 // ...
 }
 return hr;
}

Requirements

See also

DWM Blur Behind Overview