c++ full transparency window but still read text for example

I'm trying to do something like Rainmeter do to its windows, that is use t开发者_如何学JAVAhe full transparency in a window but we still read the text of each window.

Anyone can explain me how this is done? how we set the full transparency in a window and show certain parts of this window (like text or other things).

I can do this with regions but seems to me that it's not like Rainmeter does, anyone knows how can i do this in c++ (WinXP and above)?

Thanks

You need to use layered windows.

In answer to your comment:

To make part of the window transparent, call the UpdateLayerdWindow function and give it a partially transparent background image.

You can also pass the ULW_COLORKEY instead of giving a partially transparent background image, and every part of the window that is the color you specify will become transparent. (most people use magenta). However, if you do it this way, you can't make part of the window semitransparent.