Displaying graphics on top of another full screen application; hardware overlay?

Question

On Windows (Vista32), I want to display some simple graphics on top of a fullscreen flash window (an overlay of useful information while using the flash application). What's the fastest way to accomplish it?

I think I may be able to achieve it using DirectX with the DDSCAPS_OVERLAY flag but with the only example I've found I get an exception:

E_NOTIMPL
The function called is not supported at this time

on

m_direct_draw->CreateSurface(&ddsd, &m_overlay_surface, 0)

(full code here: http://nexe.gamedev.net/files/Overlay-2005-11-21.zip)

Something relevant to C/++ or Python would help me. I'm using the latest DirectX SDK.

Thank you

Answer 1

Just create a Layered Window and draw to it with an alpha channel - in WPF, this is as easy as setting the AllowsTransparency bit on the Window

Answer 2

While the transparent layered window is useful, it doesn't appear on top of the fullscreen flash with WS_EX_TOPMOST set.

Note sure how to reply to Paul sadly.

http://stackoverflow.com/questions/925981/overlaying-on-a-3d-fullscreen-application is very relevant but while it works and flash appears to load dx9, it doesn't show on flash.