First Floor Software

UI Automation may crash Spy

There seems to be a bug in the UI Automation implementation of Silverlight 2 where the host of a silverlight application will crash when you try to use an UI Automation client on a Silverlight Application with a large number of UI elements. Hosts such as Internet Explorer, Firefox and Silverlight Spy all suffer the same consequences.

The bug seems to be a known issue and MS is working on a solution/workaround (see also http://silverlight.net/forums/t/39506.aspx).

Update @ Feb 18, 2009: this bug has been fixed in Silverlight 2.0.40115.0.

How to reproduce

Navigate Silverlight Spy to the Microsoft Health CUI Patient Journey Demonstrator application (http://www.mscui.net/PatientJourneyDemonstrator/PrimaryCareAdmin.htm) and open the UI automation tree. The root node will be shown and when you try to open the childs of this node the Spy will stop functioning. This also occurs when using a UI Automation client such as UI Spy on the Demonstrator application running in IE or FireFox.

Workaround

Unfortunately, there is no workaround available yet. This is a bug that needs to be addressed in the Silverlight 2 runtime. As soon as there is news from Microsoft I'll post it.