Just out of curiosity you can map your keyboard to take a screenshot. Most screenshot apps are just front ends for scrot, which actually does the work. In Openbox you can place the lines below in rc.xml -
<!-- Take a screenshot of the current window with scrot when Print is pressed -->
<keybind key="Print">
<action name="Execute">
<command>scrot '%Y-%m-%d--%s_$wx$h_scrot.png' -e 'mv $f ~/Pictures/ & geeqie ~/Pictures/$f'</command>
</action>
</keybind>
This tells scrot to take a screenshot when the "PrintScreen" button is hit, give it a name, save it to my ~/Pictures folder and open it in Geeqie. You can then do with it as you want. Just change the names of the folder and graphic viewer as required. Just make sure scrot is already installed.
VillageBox has screenshot commands set for keyboard and also extra options in the root menu.