Hot keys
The usual hot keys work in the editor:
- Shift + arrow for select 
- Ctrl + C for copy 
- Ctrl + X for cut 
- Ctrl + V for insert 
- Ctrl + Z for undo 
- Ctrl + Y for repeat 
Mouse
Of course you can also select with the mouse and use your browser's editing features.
 Linux / X11: A left doubleclick selects and copies a word, and a click on the middle mouse key is insert. Linux / X11: A left doubleclick selects and copies a word, and a click on the middle mouse key is insert.