@Dahu: Please keep to English on the forums.
What you are looking to achieve does not exist per say, but I believe you can look into the "Paster" object and achieve the zoom/magnifying glass effect you are looking to do.
@barbisio: Look into rexrainbow's work, I think he made something that might work like that.
If you're looking to have the data displayed at edittime though, this is just not possible.
If you want it for debugging purposes, look into C2's debugger