as far I understand ( spanish ), the image is stored inside a resource ?
The problem :
You need a alphachannel-Image ( 32bbp ), to get clean borders.
It means, the used Resource-editor MUST support this format,
otherwise the quality is very bad.
I hope I understand the problem ?
What resource-editor You are using ?
Only a alphachannel-Image ( 32bbp ) shows a clean border.
A long time ago, I bought a resource editor ( never updated ), that supports this format.
I have to check the update-infos what is new.

Tested 30 days trial ( 32bbp is supported ) :
32bbpimage loaded :

The generated RC-file :

best regards
Uwe
