In the previous release, if you had a window larger than your screen, you could still take a screenshot of the entire window. This is no longer possible:

#!/bin/sh
select="$(hacksaw -f "-i %i -g %g")" 
# my window: "-i 27311718 -g 3028x4036+-554+-1478", screen size is 1920x1080

# new release:
shotgun -f png $select test-1
# stderr: Invalid geometry

# old release (in build dir):
./shotgun -f png $select test-2
# makes big image

Note that using the OLD release of shotgun in an interactive shell also does NOT work:

$ ./shotgun -f png -i 27311718 -g 3028x4036+-554+-1478 test-3  
X Error of failed request:  BadMatch (invalid parameter attributes)
  Major opcode of failed request:  73 (X_GetImage)
  Serial number of failed request:  20
  Current serial number in output stream:  20

While it does in a file. I don't know why. Tested in zsh, bash, and dash.

This feature might seem almost useless, but I do use it from time to time for things like taking screenshots of MPV or feh when I want to share a large image quickly, or capturing GUI programs with window size dependent behavior, like how spek (audio spectrum analyzer) only increases resolution with window size.