When loading a Uppaal model in XML form where the global declaration section is missing, Uppaal will load it, but Java will spit out a null pointer exception when trying to edit the declarations. Editing other textual parts of the model afterwards does not work any more. Missing local declaration sections are not a problem. A missing instantiation section is also not a problem. A missing system section causes Uppaal to hang when loading the model. The attached models can be used to show these problems. These problems only occur when using models modified by software other than Uppaal itself.
Created attachment 41 [details] Model without global declaration section
Created attachment 42 [details] Model without system section
I just noticed that the global declaration section is left out by Uppaal when saving a model where the global declarations are empty (i.e., when the initial comment is removed and the model is then saved).
Confirmed. A fix will be checked into CVS later today.
A fix for the problem with global declarations has been checked in (the declaration tag is optional, so of course the GUI should work even when it is not there). The system tag is not optional (see the DTD), but I fixed the GUI such that it actually loads the file correctly anyway. I changed the server/verifyta such that an exception is thrown when the system tag is missing. Resolving bug.