Tracked down the 'blank window' bug that has hit me twice

So I had posted on the Facebook Dorico page that after a crash, any subsequent restart of Dorico produced blank windows for documents and the hub (basically any window that wasn’t a Preferences Dialog). I figured out how to fix it. It turns out, it’s my setup, which is a MacBook Pro with the lid closed, connected to an external monitor.
In order to get Dorico to draw windows properly again, I had to open the MacBook Pro and restart it in the original laptop window. The window problem would be gone (all windows looking normally) and then closing the laptop and reconnecting the big monitor continued to show the windows normally.
This was a real head-scratcher, because the first time it happened I did everything, including re-installing Dorico, and only after several restarts (and I believe, ultimately this laptop video restart) did things return to normal. BTW, I checked the hard disk and there were no issues, so this was a case of Dorico not remembering the draw routines after an unexpected restart, and not an issue involving corrupted application files or the like.
Don’t know if there are many others running Dorico on a closed MacBook Pro connected to a Philips monitor via HDMI connection but if so, I’d be curious to see if you ran into this issue as well.

I too run my MacBook Pro in “clamshell” mode, so it only ever uses the external display, but I’ve not run into this particular issue.

However, I know that the Qt framework that Dorico relies upon has some peculiar and sometimes unhelpful behaviours when it comes to managing windows across multiple displays, so it’s certainly not impossible for it to get confused about which display to use. The thing that’s curious about this case is that when your MacBook Pro is running with its lid closed, there is “only one” display.