message WindowTraits

Pinned above the rest of the workspace from the first frame, as the window menu's "Always on Top" does — and the user can still un-pin it there. Not an overlay: the desktop's own launcher and switcher outrank pinned windows because the compositor knows them, never because a client asked.

The application places and sizes this window, and the user does not: no drag to move or resize it (title bar, edges, Mod+drag, BeginMove), no maximize or fullscreen from the title bar, the context menu or the keyboard, no Center on Screen, and no remembered frame. SetMaximized and SetFullscreen still work — they are how the app states the frame it wants, and nothing but a client calls them.

One window per appId: a second CreateWindow for an application that already has one brings that one here instead and raises AlreadyRunning. An empty appId has no identity to compare, so it is never refused.