Add logic to check if the checkbox has already been disposed instead …

[kenman345]

…of trying to use it.

fixes #9

Fair warning, have not tried this, just thought this might be whats needed, but it should at least be a start.

[ROMaster2]

I'll have to see if I can consistently invoke this exception to know if this solution works.

[kenman345]

yea, seems not exactly easy/fun to reproduce

[kenman345]

sounds like that might be why this is even happening in the first place, and that this fix probably would not help us diagnose the issue further down the line if you hadnt found that error