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When creating custom UI components you sometimes inadvertently use some resource that will be available in your application, but is not available when the GUI Builder tries to initialize and show the component. In these cases you get a dialog that pops up with the message "The component cannot be instantiated. Please make sure it is a JaveBeans component" It would be a nice to be able to see what is causing the failure to instantiate, so that you can track the problem down faster. A "Details" button could be added to the dialog that when pressed showed the stacktrace
*** This bug has been marked as a duplicate of bug 121616 ***
Note that the exceptions should be printed in the log, which you can show from menu View | IDE Log.