Calender Bug #398

Describe the bug
''PART_DisabledVisual' name cannot be found in the name scope of 'HandyControl.Controls.Simple Panel'

To Reproduce
Steps to reproduce the behavior:

1. Add a calendar to your control
2. Set the property IsEnable to False
3. See error

Expected behavior
Application crashes when page that has the calendar control with property set to IsEnable = false.