Having trouble refreshing the Windows aero preview in C#

Question

I want to refresh the aero preview that's displayed when hovering over a taskbar icon on Windows (or when Alt+Tabbing).

I found a function called DwmInvalidateIconicBitmaps that seems promising, but when I use it:

[DllImport("dwmapi.dll")]
static extern int DwmInvalidateIconicBitmaps(IntPtr hwnd);
...
int res = DwmInvalidateIconicBitmaps(MyWindowHandle);

res gets set to -2,147,024,809. When I look at the hex it comes out to FFFF FFFF 8007 0057, which seems to correspond to E_INVALIDARG according to this site.

My window handle however is valid and is used in other places successfully. Another site I came across mentioned that this error can be thrown when the DLL couldn't be loaded. Could that be the issue?

I also doesn't see this function mentioned on the pinvoke site though I do see other DWM functions, which is odd.

Windows 10 / .NET Core

Answer 1

The documentation clearly stipulates this:

hwnd

A handle to the window or tab whose bitmaps are being invalidated through this call. This window must belong to the calling process.

If this is not the case, you'll get an E_INVALIDARG error.