1) If ContentRoot is rotated, you can't move the window anymore (it just disappears when trying to move it)
To reproduce the behaviour, edit generic.xaml, change the ContentRoot transformation group to:
<RotateTransform Angle="180" />
The resize part still works OK after the rotation.
2) UpdateContentRootTransform() is never used, thus _contentRootTransform points to a null object and can't be used to obtain the current TranslateTransform.