XUL:Richlistbox
The <richlistbox> widget is supposed to be a <listbox> like widget for XUL content. It is currently implemented as a widget on its own (source) and supports only single-select mode. Multiple-select mode will come (see bug 298371), the question is however in what way.
Arguments for making <richlistbox> inherit from <listbox>
- Less duplicate code
- As a consequence: more stable code since it is used more frequently
- Identical API for all kinds of listboxes
- Consistent behavior (see e.g. bug 298993 or bug 325235)
Arguments for keeping <richlistbox> an independent widget
- nsIDOMXULSelectControlElement's appendItem and insertItemAt methods are in their current form pretty pointless for rich content
- the current API is pretty different from the <listbox> API - which either means breaking all current users of <richlistbox> or carrying around a lot of backwards-compatibility methods
- while <listbox> and <richlistbox> are very similar, they still differ in details; an identical API might confuse developers more than a clearly different one
- there would be no need to think about implementing <richlistcell>, <richlistcol>, <richlistcols>, <richlisthead> and <richlistheader>
Current Usage
The <richlistbox> widget is currently used in the following components in the Mozilla source tree:
- Toolkit Downloads manager
- Toolkit Extensions/Themes manager
- Toolkit Update history
- Lightning's ToDo-list
- CCK wizard example
One further notable example is the Console² extension which features its own multiple-select <richlistbox> (if you install it, you'll get FAYT in the Downloads/Extensions/Themes managers).