linux screenshot only current window
PrtSc – Save a screenshot of the entire screen to the “Pictures” directory.
Shift + PrtSc – Save a screenshot of a specific region to Pictures.
Alt + PrtSc – Save a screenshot of the current window to Pictures.
Ctrl + PrtSc – Copy the screenshot of the entire screen to the clipboard.
Shift + Ctrl + PrtSc – Copy the screenshot of a specific region to the clipboard.
Ctrl + Alt + PrtSc – Copy the screenshot of the current window to the clipboard.