Sublime Text 2: Disable cursor position overwriting characters (like vim replace mode)

If you go to Preferences->Key Bindings (Default) and search for "overwrite" you'll find the key binding. At least on Windows it's set to the Insert key. You probably managed to hit some key combo to emulate that key on your keyboard. If it happens again and you can't figure out how to get out, just change it to CtrlAltShiftI (unused in my default setup) and you should be good to go. Make sure that you put this entire line in your Preferences->Key Bindings (User) file, in between the square brackets:

{ "keys": ["ctrl+alt+shift+i"], "command": "toggle_overwrite" },

The , at the end is only needed if you have additional entries in the file.

{ "keys": ["super+alt+o"], "command": "toggle_overwrite" }

This setting is present in Preferences -> Keybindings - Default

i.e. on Mac Command+Alt+O

On a Mac, fn + return works as insert.