KSnapshot is KDE's in-built screenshot grabber. Just hit the PrtScr key and you can save a screenshot in a wide range of formats. But there's more to KSnapshot than just formats.
Capture Mode has five snapshot options. Each hides the KSnapshot applicaton window and turns the cursor into a crosshair (+) but how you actually capture the shot depends on which mode you've selected.
* Full Screen : left-click to snap the whole screen.
* Window Under Cursor : left-click to snap the window you're pointing at.
* Region : left-click and drag with the mouse to select any area you like. Resizing handles around the sides of the selection enable further adjustment, or you can reposition the selection area by clicking and dragging it about. Press ENTER to actually make the snapshot or ESC to quit.
* Section of Window : move the cursor over an open window and you'll find it's individual sections highlighted by a red boundary box. Left-click to snap the one you want.