Binary incompatibility in Silverlight for Windows Embedded in May 2014 Update Onwards

Last Year Michel blogged about a binary incompatibility introduced in the May 2014 update of Compact 7 which broke existing Silverlight for Windows Embedded code including pre-compiled system apps.

The XAML In The Hand library was also affected. It turns out that one of the breaking changes was the addition of the GetTemplateChild method to the IXRControl interface. Previously this was present in the Compact 2013 codebase but not Compact 7.By adding a method to an existing COM interface (breaking the rules of COM again) means that the vtable offsets of all the methods in interfaces which inherit from this one are all shifted by one. Our next update will incorporate a fix for this (as well as exposing the GetTemplateChild functionality to the managed API) and will support Compact 7 from the May 2014 update onwards. The current released version of Compact 7 is the November 2014 update.