Scintilla-based editors, GTKsourceview-based editors (I just tried with Scite and Gedit) and Emacs all correctly position the cursor when using the arrow keys and proportional fonts.
As for lining up similar constructs, I mostly code in Python, and the PEP 8 style guidelines explicitly forbid that.
As for lining up similar constructs, I mostly code in Python, and the PEP 8 style guidelines explicitly forbid that.