[ivanbakel]

As a rule of thumb: if you ever ask "why not", and the alternative you're proposing is more complicated - that is normally why not. Lots of UI/UX bugs can simply be attributed to the programmer taking the most simple possible design.

In this case, the async logic is not advanced. In fact, I'm willing to bet that this is what happened: at first, the file-opening was synchronous in the GUI. People complained that opening certain files locked up the file picker, so a developer sticks the file-opening code in a background thread. This produces the above bug, without complicating the input design - in fact, preventing the bug requires making additional changes to the code in some way.

[ballenf]

Thanks that makes total sense. And a good rule of thumb for me to remember.