2011/6/8 Strainu strainu10@gmail.com:
Yes, it does depend on the project, but I'm pretty sure that in most projects there are some chunks of js in Common.js that simply should not be disabled.
In my opinion any custom ui feature should be optional, because it will never satisfy all users. It will also simplify developing and testing new versions of a gadget, by giving users an ability to turn off old version and turn on the new one. User having trouble with interfering scripts will be able to find out which ones by selectively disabling gadgets. Getting rid of MediaWiki:Common.js may not be feasible for all projects, in the end it is all up to sysops how much freedom they are willing to grant to contributors and viewers.
Regards, Ildefons Stułbia