In-page scrollbars - Yes or no? Or maybe

Is it bad UX to put a scroll bar in a module with a list, is there ever a case to use this?

My developer says its a bad idea and just annoys users.

Should this kind of thing never be used?

^{download bmml source – Wireframes created with Balsamiq Mockups}

Facebook do something like this on this menu item below to choose your page you want to act as, but I do find the interaction a little irritating, so perhaps I've answered my own question - lol

Answer

You definitely should try to avoid nesting scrollable areas inside a webpage if possible: scrollable areas are breaking page interaction (nested block will be scrolled instead of outer page itself while using tracking pads or mouse wheels for scrolling).

There are some exceptions:

1. 
   

   You may use nested scrolling panes if they're shown temporary (like in Facebook example you've mentioned in your question: the scrolling list in popup which is shown for a moment and will not break the page scrolling itself).

   
   



2. 
   

   Editable areas like comments may be scrolled while being edited (and reverted back to non-scrollable mode then editing is done).

   
   


3. 
   

   Web apps which may occupy the whole browser window and avoid scrolling of the content by using dynamic layout so it's OK to use nested scrolling panes (since main content area could never be scrolled anyway).

   
   

And in a case if you can not avoid using scrollable areas always showing a scrollbar is a good idea: users will notice that the area can be scrolled and will be aware of the area behavior.