MahApps/MahApps.Metro — pull request #201 by Shazbot (2012-09-16 15:29:44+00:00)
Title: Fix for #134: InvalidOperationException on validation tooltip opening

Repro is here: https://github.com/Shazbot/MahApps.Metro/compare/tooltipExceptionRepro

If I start typing text into the textbox I get an exception.