This is just a very simple but quite useful Keyboard Maestro macro example to get automatic autocomplete in Mac Os apps. The autocomplete popup window is displayed after any 4 characters. You can change it for 5, 6 or whatever.
Tested in Stickies... but it should work in any Mac OS (just make sure to activate it only for Mac OS apps, otherwise the F5 key will activate different things).
Hmm... it works but it can also interfere with your work.
I should have tested it a bit longer, my apologies.