SCREEN SHOTS FROM WINDOWS
    Gimp Create / Screen Shot...
        On ArchLinux requires setting...
        Can select full screen or a Window.
        Unfortunately, it barfs sometimes, perhaps because Windows sees that
        passwords are present?
    PrintScreen key, then Gimp Create / From Clipboard.  Captures full screen.
    Alt-PrintScreen key, then Gimp Create / From Clipboard.  Captures Window.

IMAGEMAGICK
Cropping with imagemagick.
    Put a ! right after the geom/offset VALUES to get rid of the layer offsets.
     (The +repage settings has no effect for me).

ImageMagick pixel coords are 0-based.  (0,0) is the top left pixel.

To CROP with ImageMagick (as opposed to rescaling, etc.), use
    -crop WxH+X+Y

Generally use -resize for resizing, not -size or -geometry, etc.
Use -thumbnail for the obvious special purpose.