VSTO Runtime Update to Address Premature WPF UI Thread Shutdown

In the VSTO Runtime released a month and a half ago (version 10.0.50701), a small regression was inadvertently introduced, which is fixed in today’s update to the runtime.

The issue impacts add-ins that call Globals.Factory.GetVSTOObject on a Word document or Excel workbook.  If Windows Presentation Foundation (WPF) is used for the add-in’s user interface, and if the document or workbook corresponding to the “GetVSTOObject” function call is closed, the WPF UI Thread may shut down prematurely.  When this happens, rendering for WPF controls will be broken until Excel or Word restarted.  While this issue only manifests itself on certain system configurations (primarily touch-enabled devices) and only under very particular conditions, we recognize that this can be a serious scenario-blocker for certain add-ins.  Today, we are releasing a new version (10.0.50903) of the runtime that takes all the enhancements of the previous VSTO runtime release, but resolves this particular issue.

The update is cumulative and can be installed both on a clean machine and on top of an existing VSTO runtime installation.  As always, the latest VSTO runtime can be downloaded from our “permalink” at http://go.microsoft.com/fwlink/?LinkId=140384.  The update will also be distributed as part of Windows Update in the upcoming months.  In the meantime, if you would like to ensure that your users have the latest version installed, please follow the instructions for creating/modifying a bootstrapper package from a previous blog post, substituting the latest version number (10.0.50903) into the following properties in product.xml:

<BypassIf Property=”VSTORuntimeVersionInstalled” Compare=”VersionGreaterThanOrEqualTo” Value=”10.0.50903“/>

<BypassIf Property=”VSTORuntimeVersionOfficeInstalled” Compare=”VersionGreaterThanOrEqualTo” Value=”10.0.50903“/>

~ Michael Zlatkovsky | Program Manager, Visual Studio