Automation Focus Change handler in WPF apps hangs the UI - by Bill van Melle

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  Fixed<br /><br />
		This item has been fixed in the current or upcoming version of this product.<br /><br />
		A more detailed explanation for the resolution of this particular item may have been provided in the comments section.

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ID 450706 Comments
Status Closed Workarounds
Type Bug Repros 0
Opened 5/14/2009 3:20:10 PM
Access Restriction Public


Within a WPF app, using Automation.AddAutomationFocusChangedEventHandler causes the  UI to hang when the user interacts with the UI.  I've already followed the advice in to add the handler on a non-UI thread, but this does not help.
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Posted by DBoss on 7/2/2009 at 1:46 PM
I've also tried the workaround and doesn't seem to work. Is there going to be some fix for this bug for Vista and XP?
Thank you for your attention
Posted by Bill van Melle on 6/23/2009 at 2:25 PM
This workaround doesn't even work in the toy sample code that I sent you. Did you try it there?
Posted by Microsoft on 5/29/2009 at 2:23 PM

This is an bug in the OS component of UIA and is fixed in Win-7. But, you could workaround this issue in your code by adding following piece of code in method where you attach the handler. Let us know how this works for you.

CacheRequest cr = new CacheRequest();
cr.TreeFilter = Condition.TrueCondition;

WPF team
Posted by Microsoft on 5/20/2009 at 5:35 AM
Thanks for the feedback. We are escalating this bug to the product unit who works on that specific feature area. The team will review this issue and make a decision on whether they will fix it or not for the next release.

Thank you,
Visual Studio Product Team
Posted by Microsoft on 5/18/2009 at 2:49 AM
Thank you for your feedback, We are currently reviewing the issue you have submitted. If this issue is urgent, please contact support directly(

If at any time your issue is closed unsatisfactorily, you may edit your issue via Connect and change the status to “Active.”

Thank you,
Visual Studio Product Team