GUI state after interupting with :

After switching to untitled 17 and back to test_timeout:

Sometimes it is necessary to switch back and forth twice.

Does this mean that the kernel did not receive the interupt?

For the legend in the image below I would have expected a black image and not a white

I was wondering if Maple could be setup in a way that no parallel processing is performed (as on a single core)?

I know, it's a poor way to test an algorithim/method for thread safety (i.e. deterministic behaviour). But it is better than nothing.

Are there other ways to test for thread safety?

expr:=cos(x)^2;
expr=combine[trig](expr);
(x->x=combine[trig])(expr);

Update:
Same outcome with

expr=`combine/trig`(expr);
(x->x=`combine/trig`)(expr);
                          2   1            1
                    cos(x)  = - cos(2 x) + -
                              2            2

                           2               
                     cos(x)  = combine/trig

When executing the attached work sheet, the output

changes to

Why is that (local seetings maybe?) and how to reproduce the former, more compact output?

Download Output_formated_with_rational_factor_.mw