You never want to block your UI thread for any amount of time a user would notice say more than 20ms. And if you use async or another thread you can always upda

You never want to block your UI thread for any amount of time a user would notice say more than 20ms. And if you use async or another thread you can always update the UI to disabled with spinner state. This is all less convenient for the programmer but much better for the UX. Blocking the UI blocks it all, even the close button!