Error when choose class path SP12

Question

When I create Part, at step choose the class path. It raised an error, and can not display the class path tree 
 I debugged on Chrome and found the error 
 
 How can I fix it? 
 Thanks

Christopher Gillis · Answer

Hello, 
 It looks like this error is being thrown in a custom form event you have on the Part ItemType. It looks like you're trying to get the main window in order to open a dialog for the user. There's a standard aras function that you can use to achieve this that should resolve the error you're seeing. 
 top . aras . getMostTopWindowWithAras (); 
 Please try to use this function to set the value of the aWindow variable in your method. If you'd like more information on using custom dialogs within a javascript method, you can see this b log post . 
 Chris 
 Christopher Gillis 
 Aras Labs Software Engineer