Freezing/CPU spinning bug in Silverlight 4 RichTextBox and Right to Left text

Freezing/CPU spinning bug in Silverlight 4 RichTextBox and Right to Left text by Adam Hathcock

Active

Type:	Bug
ID:	570272
Opened:	6/24/2010 4:12:15 AM
Access Restriction:	Public

Workaround(s)

view

User(s) can reproduce this bug

There seems to be a infinite loop occuring the internal RichTextBox's native code in MeasureOverride.

The issue doesn't seem to occur if everything is statically defined in XAML. It only happens when Runs (with RTL text) and InlineUIContainers are added programmatically to the RichTextBox model.

It is possible that only certain characters cause this. This can be demonstrated with samples with Arabic and Hebrew text.

As an aside, there also seems to be the same CPU spinning when GetNextInsertionPosition is called on the same bad run of text. I haven't made a sample for it but it seems related. Let me know if a sample should be created for that as well.

Details (expand)

English

Silverlight 4

Windows 7

English

It only happens when Runs (with RTL text) and InlineUIContainers are added programmatically to the RichTextBox model.

Resize the RichTextBox and MeasureOverride will cause the problem.

MeasureOverride causes the CPU to spin and freezes the Silverlight Application

Just normal operation from User interaction

File Name	Submitted By	Submitted On	File Size
RichTextBoxFreezeHebrew.zip	Adam Hathcock	6/24/2010	120 KB
RichTextBoxFreeze.zip	Adam Hathcock	6/24/2010	117 KB

Posted by Microsoft on 6/24/2010 at 8:31 PM

Thanks for your feedback.

We are rerouting this issue to the appropriate group within the Visual Studio Product Team for triage and resolution. These specialized experts will follow-up with your issue.

Posted by Microsoft on 6/24/2010 at 5:02 PM

Thank you for your feedback, we are currently reviewing the issue you have submitted. If this issue is urgent, please contact support directly(http://support.microsoft.com)

Posted by Adam Hathcock on 6/24/2010 at 4:13 AM

There is a silverlight.net forum post for this: http://forums.silverlight.net/forums/t/184138.aspx