Taking a PNG screenshot of a window, but keeping the aero transparency

Question

Some time ago, I stumbled upon an excellent article about taking screenshots of specific windows in .NET, and doing something with black and white color rectangles behind those windows in order to preserve the aero effect when saving a screenshot to a PNG. Well, I can't find that article anymore, mainly because crap sites and other stuff not at all associated with taking screenshots SEO'd their way into Google's results. Does anyone know how I can take a screenshot of a specific window while preserving the aero effect?

Answer 1

I think you meant this link. It describes how to revert alpha blending to get the "true" alpha values back. Basically you have to put a white rectangle below the window, take a screenshot and do the same with a black rectangle. Then you can regain the alpha channel of the window, as described in the blog post linked above.

EDIT: Sorry, now i posted the corrected link.