Banana SplitButton [A WPF-specific fix for SplitButton and some code analysis improvements for the Silverlight version, too]
I've previously written that one of my ContextMenu test cases for the April '10 release of the Silverlight Toolkit was to implement a quick "split button" control for Silverlight using Button and ContextMenu. Though it wasn't my goal to build a general-purpose control for widespread use, there's been a lot of interest in SplitButton/MenuButton and I followed up with a few fixes for the Silverlight version and "official" support for WPF.
That might have been the end of the story - until Fabio Buscaroli contacted me to report an issue he was seeing with the WPF version (follow our exchange here). At first, I thought the problem was related to the DataContext not inheriting properly - and while that was true, it wasn't the whole story! When Fabio told me the tweak for DataContext I'd suggested didn't solve his RoutedCommand scenario, I had a look at a simple example he posted and realized the DataContext problem was a symptom of a larger issue: that the ContextMenu wasn't a logical child of the SplitButton. As soon as I solved that problem, it fixed Fabio's scenario and the related DataContext issue I'd discovered during my own investigation.
Aside: None of this applies to Silverlight because that platform doesn't expose the notion of a logical tree the way WPF does.
While I was working on this fix, I noticed full code analysis wasn't enabled for the SplitButton assemblies; I turned it on and addressed the handful of warnings it generated. Most of the changes won't matter to you, but one of them will: the namespace for SplitButton/MenuButton has changed. These classes now live in the Delay namespace - which is consistent with the rest of the sample code I post to my blog. Upgrading existing projects to the latest code will require a tweak of the XAML's "xmlns:" prefix and/or a tweak of the code's "using" statements. Otherwise, there have been no behavior changes to the functionality of SplitButton on Silverlight or WPF, so everything else should continue to work the same as before.
It's been great to see the positive response SplitButton and MenuButton have generated. Thanks for everyone's help trying these controls out, finding issues, and reporting them!