Interesting that they default QuickEdit mode to on now. In Windows 2000 (supposedly), they had to roll a hotfix because some well-meaning engineer made the same change without thinking of backwards compatibility. [2] Kinda shows how times have changed.
[1] "One of the top requested changes we’ve received over the years is to have quick-edit mode enabled by default. Tada!"
I remember on a few occasions staring puzzled at some script at work, which was taking a lot more time to run, than normally.
Like an hour instead of few minutes.
I remember also, that coworkers had the same issue. One of them left work once, leaving a long process running. He came back the next day and it hadn't finish yet. He was ready to file a bug report somewhere, when we found out...
If you click on the command prompt with the QuickEdit mode turned on, in a "wrong way", the underlying process will be frozen. It's because the input and output streams are blocked indefinitely, until you finish your selection and the content gets copied to the clipboard.
So, why would you want to click on it? There is a common pattern people use for long running scripts: they push the window somewhere in the background, but leave a little space you can click on, so that you can view it very quickly.
The "wrong way" of clicking is when you do click-drag instead of a point click. It goes automatically into the QuickEdit mode freezing everything underneath it.
