Binding to user defined class selection

Hi,

I have a problem binding to user defined class (extended from gridpanel) selection if it has a viewModel defined.

Please take a look at the following fiddle http://ift.tt/1r0ZLyw

The binding should determine the right hand side panel to be disabled at start-up but it's not. It only works if the user defined class doesn't have a viewModel defined.

Is there a way to make it work even if the user defined class has it's viewModel defined?

Thanks,

Danny

Binding to user defined class selection