I discovered with what Ulf discovered about this issue how to manage this thing, so that it is possible to get the pop up window before the window of the Synchron Player.
This works only if you have opened just one Synchron Player instance (of course beside the main window of Dorico) and you click on something in the Synchron Player that normally gives a pop-up menu, and you type ctrl + tab, then the popup menu appears. I hope this helps you.