Thanks Panda X and Eoin for you quick reply,

I've read about the DWM's blur shader. It's sad.
I tried to get some info about 7 DMW. Do have an idea, a link that could help?

Thanks at all

Dear Users&Writers this is my first Post,
I've read a lot about the window frame corners. So i know that this is not the first time that someone asked this.

This was very interesting, but didn't help at all

Corners in window frame...
http://vistastylebuilder.com/forum/index.php?topic=1127.0

Where this transparency?
http://vistastylebuilder.com/forum/index.php?topic=739.0

I've have those two png files...
Windows and Caption Buttons > Aero > Dwm Window > Frames > Normal > Bottom
Windows and Caption Buttons > Aero > Dwm Window > Frames > Normal > Top

and I'm not able to get nearly 100% transparent, "squared" Frameborders without having those tiny, little round corners,
were there seems to not 1Pixel.

There must be a way to solve this problem, with the twelve missing Pixels, in each corner.

Attached, the pictures.