It appears that one cannot simply drop a layer into another document when the documents are set up in windowed mode. Steps to reproduce: 1) Have two windows opened in windowed mode. 2) Paint on one windows. 3) Drag and drop into another document windows. 4) Proceed to see exporting window. 5) See a duplicate of the painting layer on the window you originally painted on. Operating System - Windows 10 x64 Krita Ver- Krita 3.3.1
Considering I don't think this was ever possible, we should probably set it to wishbug.
I was able to do it with tabs mode just fine. I drag and drop layer into the tab, and then I drop into the layer docker.
I have tested with the latest pre-alpha, and you can certainly drag and drop layers from one subwindow to another subwindow. I'm not sure if this has worked before and to my memory it didn't, but I believe one should consider this resolved as it works. All you need is to avoid the title section, and then go to layer docker dragging the layer, and bam. It worked on subwindowed with latest pre-alpha.
Oh, and I forgot to mention, you can't drag and drop to any order you want. It has to be the lowest group for it to be successful on subwindowed mode or tab mode. That's the only bug I know of for this function.
Hey, I have came to report that you can finally drag and drop any layers from one document to another in any order. This bug has been solved. Tested with both tabs, and subwindows. There's still the inconvenience that you can't just drag and drop without having to hold layers and moving in to the tab first, but nonetheless, as that's another issue, it is solved.
Closing then.