BEAUti prior dialog box won't open

[maxbiostat]

I'm on Linux, using trunk and release BEAST. Steps to reproduce:

• Select skygrid as your tree prior;
• In the Priors tab, try to click the little box for skygrid.precision in order to change the hyperparameters on the Gamma prior
  Result:
• the dialog box won't open.

[rambaut]

As it is currently implemented, the prior on the skygrid and skyride precisions are fixed. If this is the correct behaviour then the button should be visibly 'greyed out'. I am not sure about the rationale for now allowing other priors.