Disable special characters in OS X (no 3rd party)
RubyMine comes with handful of mnemonics which are supposed to boost your productivity. However ones that are combined with
alt keys can sometimes cause unexpected behaviours since some of them are bound to special characters (e.g. ™, Ó, µ ...).
You can disable special characters by choosing
Unicode Hex Input as an input source (System Preferences > Keyboard > Input Sources > Others).
Alt + key won't interfere with any keyboard shortcuts. Happy RubyMining!