crash on win7

[bledyy]

Fast double clicking on the icon in the top left corner crashs the program.
On version 1.0 this error message didn't pop up, so I thought it was a kind of a feature, but after the update it pops up what's on the .gif
I am using Windows 7, so it is likely that this error only occurs in this version.

By the way: Please add the ability to add custom icons! :)

[dbwiz]

For other feedback, I'll confirm this does not happen on windows 10 (64 bit, build 19045. CT: 1.1.4 nolatex, install, CTB).
Instead, CT closes normally (and backs up the file as expected).

[csttsn]

That's the same issue that is also discussed here: #2579