Hi.i guess you want to have a TextBox like this:
<TextBox Height="150" Width="150" Background="LightGray">
<TextBox.LayoutTransform>
<TransformGroup>
<TransformGroup.Children>
<RotateTransform Angle="90"/>
</TransformGroup.Children>
</TransformGroup>
</TextBox.LayoutTransform>
</TextBox>
isn't it ? if i make a mistake,please tell me.i will try to help you.
Good Luck