message ActiveWindow

Whether the window is pinned above the rest of its workspace — the state of the checkmark on the panel's Window menu. Re-posted when it changes, from that menu or from the title bar's.

The application the window belongs to — WindowInfo.appId, the same string. A window that exports no menu still gets an application menu from the panel (its name over a Quit), and this is what names it. Empty when the client never said.

Object path of that dbusmenu interface. Empty with menuService.

DBus service that owns this window's com.canonical.dbusmenu object. Filled from the KDE Wayland AppMenu protocol (org_kde_kwin_appmenu) when the focused surface has called set_address. Empty for Lava clients and X11 clients (they register under surfaceId on the AppMenu registrar) and for windows that export no menu.

Unix pid of the focused client. Qt5 on Wayland calls RegisterWindow with QWindow.winId(), which is often 1 and never the compositor surface id; the panel then matches the registrar entry by this pid. 0 when unknown (Lava clients, or a window with no client).

The key this window's menu is registered under on the AppMenu registrar.

Equal to surfaceId for Lava clients and native Wayland ones, which is what they pass to RegisterWindow. X11 / Xwayland clients pass their XID instead — a different number, in a namespace that can collide with compositor surface ids — and looking the menu up under surfaceId is how those menus never appeared. A panel that wants the window wants surfaceId; only the registrar lookup wants this.

0 when nothing is focused — the desktop, or the last window closing. Panels should read it as "show nothing" rather than "keep the last".

The compositor surface id, and the same number WindowInfo.surfaceId carries. Menus are looked up under registrarId, which is not always this.

What the window calls itself, so a panel showing a title does not need a second call to learn it.