Another good free implementation that seem to have it all:
http://huydinhpham.blogspot.com/2008/09/wpf-drop-down-and-split-button.html
- The split button can be used in the toolbar and has a proper toolbar style. It can also be restyled if you want.
- Dropdown menu is exposed via its own property - i.e splitbutton can have it's own context menu separate from the dropdown one (even though it seems illogical it can be useful in some cases - like toolbar context menu that pops up when you right click on a button placed in the toolbar).
- The dropdown menu is standard ContextMenu - i.e. content can be databound, menu items restyled etc.
- Both the main and the dropdown parts of the split button have command properties associated with them.
