Talvez Shutter , ele tem algumas dependências do GNOME (algumas são opcionais).
Shutter is a feature-rich screenshot program. You can take a screenshot of a specific area, window, your whole screen, or even of a website – apply different effects to it, draw on it to highlight points, and then upload to an image hosting site, all within one window. Shutter is free, open-source, and licensed under GPL v3.
Ou você pode escrever um script que peça confirmação e vincular isso à chave PrtSc
.