MahApps/MahApps.Metro — pull request #75 by jaohaohsuan (2012-04-13 02:31:41+00:00)
Title: Rewrite TextBox Text not aligned issue.

I have solved the problem by setting textBox VerticalContentAlignment = Center
When textbox is singleline ,text will be located in vertrical center, when textbox is multiline ,text will be located in top