Repeated selection of order of evaluation

[sumba101]

issue

Expression tree allows for repeated selection of the order of simulation button. this leads to filling up of the stack which a)if action is repeated till stack is filled, causes stopping of simulation b)if action doesnt lead to filling of stack, the extra cells of the stack filled by the extra selections stays in the stack till the refreshing of the page

Reproduction

here is an example where after repeated selection of preorder option the stack is full and the simulation stops

Expected fix

the selection of the order of evaluation must be suspended when a selected simulation is being executed also the simulated stack must be cleared after the completion of each selected order evaluation

[sumba101]

working on solution for this, please do not attempt