HI there,
I use Paint.net for conceptional screenshot taking and faking those screenshots. Working with the layer system is quite nice for this. I do possition my layers to look perfect, flatten them do a copy to my clipboard and paste it to open office. After that I normaly undo the flattening. But sometimes I forget to undo this and just work on - recognizing to late that i did the changes to the flatened layers...
I don't know how complicated it is, but it would be nice if there would be a way to copy all (visible) layers merged.
Flod