Allow conditional compile statements in XAML markup
Allow the XAML markup editor to allow conditional compile statements so that a developer could have #ifdef statements in their markup
Support conditional compilation inside Xaml to account for Silverlight/WPF differences in shared markup.
Understand the design-time tooling experience for this could be a lot of work.
Thank you for using Visual Studio and for your commitment to improving it. We are currently evaluating whether we will be able to include this into the product. We will be providing an update soon.
Program Manager, Visual Studio
James Abbott commented
This!! Lots of times when I'm debugging I'll use a standard resource dictionary, but when in Release Mode I want to use a cached (I'm sure you've heard of it) StaticResourceDictionary. This is just not possible as far as I can tell currently, I'm sure there are dozens of other uses for this though!