Help wanted on SIMPLE task

[Bengt Nilsson]

Hi!

I am very new to wx programming and I need help on a simple task.

How do I make a simple selection dragbox (using e.g. OnMouseEvent )  
in a graphics window without destroying what's in it?
I have the "Cross-Platform GUI Programming whith wxWidgets" book, and  
I think I have seen the source listing for the method there, but I  
just can't seem to find int.
I have gone thru it several times and failed.

I do not want to paint anything in the graphics window, I just want  
to make a flickering frame over the content to select an area to get  
input to a zooming in function.

Extremely standard, apparently too simple to be demonstrated in  
wxWidgets samples, since I cannot find it there.

Bengt