To extend a selected region that was selected with the mouse,
you hold the shift key while clicking.

See also terminal shortcuts.
Shift+Ctrl+tnew tab 
Shift+Ctrl+wclose tab 
Shift+Ctrl+nnew window 
Ctrl+{PgUp,PgDown}change tabs 
Shift+Insertpaste from selection buffer, or if that's empty the clipboard 
Ctrl+Insertcopy selection to clipboard 
Shift+Ctrl+vpaste from clipboard 
Ctrl+ClickOpen URL under mouse cursor 
© Sep 9 2005