@fc501b69 

Sorry, disagree. Read-only means "read only"...not write/modify.  I've run into this situation as well, and I get it's irritating.  So maybe an option to "allow modify" and only allow "save as..." (as usual), but nah, if I open something as read-only it should only be readable. 

 @6973e3d1 

Why wouldn't it sufficient just to get a warning that you're modifying a read-only file, like in vim?