xwayland: add wlr_xwayland_surface_has_window_type()

The infrastructure to read _NET_WM_WINDOW_TYPE already exists in wlroots
(it's used for example in wlr_xwayland_or_surface_wants_focus()). But
the window type isn't easily accessible to the compositor because the
atoms to compare against are private to xwm.c.

labwc has recently gone to a fair amount of effort (including opening a
whole new xcb connection) just to get the needed window type atoms:
a04b394e59

It seems much cleaner to add the remaining few (3) atoms to wlroots and
implement a shared function which can be used by any wlroots compositor.

v2: naming updates

include/wlr/xwayland/xwayland.h

@@ -92,6 +92,27 @@ enum wlr_xwayland_icccm_input_model {
 	WLR_ICCCM_INPUT_MODEL_GLOBAL = 3,
 };
 
+/**
+ * The type of window (_NET_WM_WINDOW_TYPE). See:
+ * https://specifications.freedesktop.org/wm-spec/latest/
+ */
+enum wlr_xwayland_net_wm_window_type {
+	WLR_XWAYLAND_NET_WM_WINDOW_TYPE_DESKTOP = 0,
+	WLR_XWAYLAND_NET_WM_WINDOW_TYPE_DOCK,
+	WLR_XWAYLAND_NET_WM_WINDOW_TYPE_TOOLBAR,
+	WLR_XWAYLAND_NET_WM_WINDOW_TYPE_MENU,
+	WLR_XWAYLAND_NET_WM_WINDOW_TYPE_UTILITY,
+	WLR_XWAYLAND_NET_WM_WINDOW_TYPE_SPLASH,
+	WLR_XWAYLAND_NET_WM_WINDOW_TYPE_DIALOG,
+	WLR_XWAYLAND_NET_WM_WINDOW_TYPE_DROPDOWN_MENU,
+	WLR_XWAYLAND_NET_WM_WINDOW_TYPE_POPUP_MENU,
+	WLR_XWAYLAND_NET_WM_WINDOW_TYPE_TOOLTIP,
+	WLR_XWAYLAND_NET_WM_WINDOW_TYPE_NOTIFICATION,
+	WLR_XWAYLAND_NET_WM_WINDOW_TYPE_COMBO,
+	WLR_XWAYLAND_NET_WM_WINDOW_TYPE_DND,
+	WLR_XWAYLAND_NET_WM_WINDOW_TYPE_NORMAL,
+};
+
 /**
  * An Xwayland user interface component. It has an absolute position in
  * layout-local coordinates.
@@ -293,6 +314,14 @@ void wlr_xwayland_surface_offer_focus(struct wlr_xwayland_surface *xsurface);
 
 void wlr_xwayland_surface_ping(struct wlr_xwayland_surface *surface);
 
+/**
+ * Returns true if the surface has the given window type.
+ * Note: a surface may have multiple window types set.
+ */
+bool wlr_xwayland_surface_has_window_type(
+	const struct wlr_xwayland_surface *xsurface,
+	enum wlr_xwayland_net_wm_window_type window_type);
+
 /** Metric to guess if an OR window should "receive" focus
  *
  * In the pure X setups, window managers usually straight up ignore override

include/xwayland/xwm.h

@@ -74,6 +74,9 @@ enum atom_name {
 	NET_WM_WINDOW_TYPE_NOTIFICATION,
 	NET_WM_WINDOW_TYPE_SPLASH,
 	NET_WM_WINDOW_TYPE_DESKTOP,
+	NET_WM_WINDOW_TYPE_DOCK,
+	NET_WM_WINDOW_TYPE_TOOLBAR,
+	NET_WM_WINDOW_TYPE_DIALOG,
 	DND_SELECTION,
 	DND_AWARE,
 	DND_STATUS,