Re: Alt->F S key sequence will sometimes insert an "s" at the current cursor location
1) Are you aware that you just posted this in an 6 year old thread?
2) Are you aware that this issue back then was about MPLAB X 2, and nowadays there is MPLAB X 5?
3) Is your issue still the issue with inserted letter "s", or do you have a totally unrelated problem?
4) Why did you not write which MPLAB X version you are using?
5) What is this "standard ALT-F key sequence", which doesn't work for you? You didn't really describe how you want it to be besides "like in MPLAB v8.92". For example ALT+F, S works for me. I don't know if the original problem with the occasionally inserted "s" is still there, because I'm usually using CTRL+S for saving instead ... like in all other competent program in the world ... ;-)
6) You can define and change any normal shortcut in Tools, Options, Keymap. You can search for the existing shortcut by function or by key. Are you aware of this?
However, note that ALT + menu-letter are default menu-shortcuts, and therefore not in this list. I think their definition cannot be removed or changed. That's default user interface behavior, although it depends on the application whether it is supported.
And if you are speaking of general application behavior, those ALT+something sequences are really not standard key sequences. Menus are language dependent and therefore ALT+something is also language dependent (e.g. German ALT+D, S instead of ALT+F, S), while CTRL+S is not. And the letter for each menu and entry can be randomly chosen by the application developer and might even be different in various applications for the same menu names.
But I agree with you, that MPLAB X is a quite slow and resource hungry IDE.