Sequence of actions is needed to trigger the bug:
1. Load the model and produce some trace using UppAal verifier.
2. Return to the simulation window and select any, but not last, step in the trace
3. Press the button "Random".
Dialog box appears "Warning: this will destroy a part of the trace! Continue?"
After pressing "No", same dialog box keeps opening again.
Mads, this might be another easy bug for you to fix.
The problem is that the random simulation is run by an extra thread. This thread doesn't notice that you
answer no to the overwrite question, thus it continous to periodically select a transition.
A fix has been checked into cvs.