Microsoft looks to patch Visual Studio 2010 bug

Release candidate has issues with the IntelliSense capability crashing

Microsoft is working on a patch to fix a problem causing crashes  in the upcoming Visual Studio 2010 IDE, Microsoft reports said this week.

The issue involves the IntelliSense coding feature in the Visual Studio 2010 Release Candidate (RC) that shipped this past Monday. IntelliSense has offered such capabilities as completion of typing and performing searches on language elements.

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Scott Guthrie, corporate vice president of the Microsoft Developer Division, said Microsoft has seen a number of people sustain an "Intellisense crash that happens very frequently on machines that have UI Automation enabled and certain devices connected."

"It turns out that a late fix right before the RC shipped modified a UI input code path that unfortunately exposed this bug," Guthrie said in a blog post. A patch is to scheduled to be released next week to fix the issue and prevent it from reoccurring, Guthrie said.

Only machines running the RC and an application or device using UI Automation 3.0 APIs are impacted. "This includes but may not be limited to RC users who are using screen reader software, multi-touch drivers, or tablet PCs," said Brittany Behrens, program manager on the Visual Studio Editor team, in the Visual Studio Blog. "Furthermore, the issue applies most commonly to customers using UIA on Windows 7 and Windows Server 2008; impact on prior operating systems should be minimal."

Workarounds include not using UIA on the same machine running the RC.  "This could include not running a screen reader, uninstalling multi-touch drivers, or disabling the touch features on a tablet PC," Behrens said. "On tablet PCs, this may mean disabling the tablet service (these instructions worked for our tablets, but please note that this link goes to a third-party site that is not supported or maintained by Microsoft).  However, we recognize that this is not an option for all users."

Users also could modify their registry. But this could produce the side effect of seeing an unhandled exception dialog the first time the bug is hit in a given Visual Studio session, she said. Also, every subsequent time the bug is hit, Visual Studio 2010 will catch and suppress the exception instead of crashing, but the caret will stop blinking and the editor will not accept input until the developer clicks on it again to restore focus, said Behrens.

A fix for the bug already has been checked in for the Visual Studio 2010 release-to-manufacturing release, said Behrens.

Featuring capabilities for developing SharePoint, Windows Azure and Windows 7 applications, Visual Studio 2010 is due to be launched April 12. A previous March 22 date for the launch was scrapped after performance issues were spotted by beta testers.

This story, "Microsoft looks to patch Visual Studio 2010 bug," was originally published at Follow the latest developments in security and software development at

Copyright © 2010 IDG Communications, Inc.

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