I was trying to figure out why in the hell my Qt apps under Wayland had no window decorations. This appears to be entirely intentional behavior and there's code you need to write to negotiate server-side (i.e. compositor-provided) window decorations, and if you *can't* negotiate that you should provide your own decorations.
There are good arguments for doing this. I see it as the Vulkan equivalent of window management: we all need something different, so you get to put the pieces together yourself.
Where the hell is the code sample for "opt into xdg-decoration" though? That's all I really want.
GOOD: If you *can* get KDE working on Wayland, hidpi experience truly is much better -- "it's better on Wayland" isn't just a meme
BAD: KWin needed to set QT_WAYLAND_DISABLE_WINDOWDECORATION to disable QtWayland's window decorations, but QML ApplicationWindows aren't recognized by KWin (or something), so QML apps under Wayland don't get window decorations
Qt Creator mixes Qt Widgets and Qt Quick in various ways; Qt Quick was designed for variable pixel densities, Qt Widgets was not, and yet, ironically, Qt Widgets seems to cope better with variable pixel densities
anyway I think I'm going to forcibly disable automatic scaling in jortjams, because the behavior is so opaque and counterintuitive on Linux and Windows. usually in this case I blame me, but I've never had this much trouble getting scalable UIs to work on iOS
if you know of a Linux software combo that handles pixel ratios > 1 with the same grace as macOS/iOS, please let me know