Setting Romanian diacritics using AltGr on El Capitan
Bit of a shameless plug: https://github.com/SaltwaterC/romanian-programmers-mac

I've created this keyboard layout as none I could find were actually following the standard for Romanian Pro. I may jump across platforms during a normal day, therefore the layout was an important thing for my use case. Works without changes since 10.8. Now I'm on 10.11.

Bear in mind there's no AltGr on Apple's keyboard. Both Alt/Option keys produce the same keycode. Using the right Option key on Apple's hardware is a matter of convention rather than a necessity.