Framing anything on screen

[John Coppens]

Hi all.

I regularly make 'tutorials' for students, and sometimes for putting on
the 'web, where I like to 'enhance' part of an image by lowering the
contrast/intensity of the rest. 

I've done that a lot of times using the GIMP, in many cases after doing
a screenshot. But I've been thinking... it would be nice to be able to do
that _before_ taking a screenshot (or just without taking a screenshot -
just to make part of the screen more important while explaining it).

I particularly like the style of the 'clip' action of the GIMP.

Is there any app that does this, if not, is there a way to do this?
(i.e., generate an all-encompassing mask over the screen, including
panel, etc). One interesting solution would be to build it into the
screenshooter.

John