Isolated transitions break the query dialog

[Jiri Srba]

To reproduce, make a new net with just one transition with no arcs,
make a new query, select CTL query and the dialog does not appear
and the GUI breaks.

[Jiri Srba (srba)]

The issue is that earlier the GUI said that orphan transitions are removed before the verification, this is not working like this anymore in 3.5.0 release.

[Kenneth Yrke Jørgensen (yrke)]

The bug is related to orphan tranistion check that throws NPE.

Old code: if(!hasShownMessage){
       messenger.displayInfoMessage("There are orphan transitions (no incoming and no outgoing arcs) in the model."
         + System.getProperty("line.separator") + "They will be removed before the verification.");
       hasShownMessage = true;
      }

New Code:
if(!hasShownMessage && !(ExportBatchDialog.isDialogVisible())){
  messenger.displayInfoMessage("There are orphan transitions (no incoming and no outgoing arcs) in the model."
         +
  System.getProperty("line.separator") + "They will be removed before the verification.");
       hasShownMessage = true;
}
else if(ExportBatchDialog.isDialogVisible()) {
  ExportBatchDialog.setNoOrphanTransitions(true);
}

NPE in call isDialogVisible():
public static boolean isDialogVisible() {
  return exportBatchDialog.isVisible();
}

export dialog is NULL.

[Kenneth Yrke Jørgensen (yrke)]

Code added in revision 961:
merged in branch lp:~tapaal-contributor/tapaal/Batch-export-PNML-XML-queries-1754675
adding batch export of files to PNML and XML