Bonjour Patrick, I too have the floating image browser and I cannot correct - I am an Intel iMac. CMD-U just causes it to appear and disappear but still floating. You stated …
You can put your cursor over the button of PhotoLab window until you see it changing to an icon with a bar and upper arrow which allow to drag it upper, and then once the space available is enough you should recover the filmstrip.
But I cannot interpret this. Is it the “main?” window or the image browser and what is the “button”.
Merci.