timeout command to run the screenshot tool with a time limit.
Add a new application shortcut with the following command.
timeout 15 bash -c 'xfce4-screenshooter -r -s $HOME'
Then, press any keyboard keys of choice for the command shortcut. I had used Shift+Print keys in my testing. Now press again the keys to invoke the command.
Why those options
-s PATH is to specify directory at
PATH where the screenshot will be saved. This option will skip the dialog to select action i.e. save, copy to clipboard that is shown before "Save As" dialog. This will reduce user interaction by several seconds.
bash -c '... $HOME' is to specify the environmental variable of Home directory of current user, using bash shell. This is convenient, rather than using direct path as
Wait or kill
timeout has reached the duration, the specified command i.e. Screenshooter will be terminated, regardless of screenshot has been taken and saved or otherwise. The command doesn't require a separate shortcut to exit the application. Wait for specified duration to exit on its own.
If the specified duration is quite long to wait, user can either:
The latter seems to be an easier workaround, rather than changing the timeout duration that depends on time taken by user to select a region and saving the screenshot with different name, if any. This is why I had suggested
15 seconds and not lesser than that.
Even better, set optimal duration (neither too short nor too long for user to wait) and use both of the workarounds that will allow user to either "wait or kill", to exit Screenshooter in Xfce.
Disclaimer: This answer suggests a workaround, not a definite solution. The best answer would be to use Esc key that is supposed to work properly with Screenshooter in Xfce. I'm unsure if the said issue is still occurring in Xfce newer than 4.10 or else.