Shutter is the best screenshot tool I’ve used on Linux, comparable in features to MWSnap freeware tool in Windows.

I love the ability to capture a selection with the mouse after pressing a key combo

Installing Shutter

Snaptic package manager comes with shutter package list. So just install shutter from there.

Configuring Keyboard Shortcut on KDE

KDE Start>Type in:khotkeys or Input actions

This opens the Input actions applet.

Rt click>New>Global keyboard shortcut>

Title: Shutter selection

Trigger: Ctrl-Shift-A (Hold down the keys you want)

Action:

/usr/bin/shutter -s --disable_systray

For Gnome (Ubuntu), do this:
Click on the Cogwheel in the System Menu >
Selection_005

Now, select ‘System Settings > Keyboard > Shorcuts > Custom Shortcuts

Click on the + button, and type:
Name: Select Shutter
Command: /usr/bin/shutter -s –disable_systray

Click Apply
Double Click on the far right coloumn where it says ‘Disabled’, and type your new keyboard shortcut.

Now when you click on Shift-Ctrl-A, you can select a part of the screen.