message ActiveWindow

Control plane

message ActiveWindow

Which window has the keyboard now.

The compositor is the only process that knows, and until this there was no way for a second client to find out — which is why a panel could show a clock and nothing about the windows it sits above. A global menu is the first thing that genuinely needs it: the menu on the panel is the focused window's menu, and a panel guessing would show the wrong app's File menu.

A window, not an app: two windows of one process are two entries, because they are two menus and the user is looking at one of them.

idl/lava.npidl:423

Fields

menuObjectPath: string

Object path of that dbusmenu interface. Empty with menuService.

idl/lava.npidl:441

menuService: string

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.

idl/lava.npidl:439

pid: u32

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).

idl/lava.npidl:446

registrarId: u32

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.

idl/lava.npidl:455

surfaceId: u32

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.

idl/lava.npidl:430

title: string

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

idl/lava.npidl:433