the trick with the "import" (imagemagick) command.
To take a screenshot(or partial screenshot), I use to use the command-line, type "import <filename>.png" and then "alt-tab" away from the console (for me, xterm) and then (usually) select a part of the webpage showing up on the browser.
However, I find in my modern X-window installations (I use osuse and slackware, with several window managers: xfce, icewm and awesome) the alt-tabbing bit doesn't work any more.
To get by, I have to reduce the size of the console so that the bit I want to capture is visible as I write the import command.
I figure this is an X problem, but it could also be an imagemagick problem (on that subject, I think I'm going to try out graphicsmagick soon).
Has any body run into this difficulty in taking screenshots? Have any solutions come up?