as in Firefox (Ctrl++/Ctrl+-) and Komodo (Ctrl+Shift++/Ctrl+Shift+-). A toolbar button would be the next best thing.
Why do you need this?
*** This bug has been marked as a duplicate of bug 41807 ***
That bug has been resolved by implementing a mousewheel based solution. This doesn't work for notepad touchpad users. Keyboard combos need to be added that are associated with zoom in/out actions.