[PATCH weston] xwm: set the _NET_WM_DESKTOP property of the windows

[Giulio Camuffo]

Some X clients use the _NET_WM_DESKTOP property to tell if the window
is mapped or not. If set, it should say the virtual desktop the window
is currently in, if unset it means the window is unmapped.
The xwm currently has no way to know how many virtual desktops does
the shell plugin have, or if it even implements the metaphor. For now
just set the property to 0, meaning the first desktop, if the window is
mapped, and delete the property when unmapped.
---
 xwayland/window-manager.c | 30 ++++++++++++++++++++++++++++++
 xwayland/xwayland.h       |  1 +
 2 files changed, 31 insertions(+)

diff --git a/xwayland/window-manager.c b/xwayland/window-manager.c
index bdfac23..08a8b2c 100644
--- a/xwayland/window-manager.c
+++ b/xwayland/window-manager.c
@@ -863,6 +863,29 @@ weston_wm_window_create_frame(struct weston_wm_window *window)
 	hash_table_insert(wm->window_hash, window->frame_id, window);
 }
 
+/*
+ * Sets the _NET_WM_DESKTOP property for the window to 'desktop'.
+ * Passing a <0 desktop value deletes the property.
+ */
+static void
+weston_wm_window_set_virtual_desktop(struct weston_wm_window *window,
+                                     int desktop)
+{
+	if (desktop >= 0) {
+		xcb_change_property(window->wm->conn,
+		                    XCB_PROP_MODE_REPLACE,
+		                    window->id,
+		                    window->wm->atom.net_wm_desktop,
+		                    XCB_ATOM_CARDINAL,
+		                    32, /* format */
+		                    1, &desktop);
+	} else {
+		xcb_delete_property(window->wm->conn,
+		                    window->id,
+		                    window->wm->atom.net_wm_desktop);
+	}
+}
+
 static void
 weston_wm_handle_map_request(struct weston_wm *wm, xcb_generic_event_t *event)
 {
@@ -888,6 +911,7 @@ weston_wm_handle_map_request(struct weston_wm *wm, xcb_generic_event_t *event)
 
 	weston_wm_window_set_wm_state(window, ICCCM_NORMAL_STATE);
 	weston_wm_window_set_net_wm_state(window);
+	weston_wm_window_set_virtual_desktop(window, 0);
 
 	xcb_map_window(wm->conn, map_request->window);
 	xcb_map_window(wm->conn, window->frame_id);
@@ -935,6 +959,10 @@ weston_wm_handle_unmap_notify(struct weston_wm *wm, xcb_generic_event_t *event)
 	window->surface = NULL;
 	window->shsurf = NULL;
 	window->view = NULL;
+
+	weston_wm_window_set_wm_state(window, ICCCM_WITHDRAWN_STATE);
+	weston_wm_window_set_virtual_desktop(window, -1);
+
 	xcb_unmap_window(wm->conn, window->frame_id);
 }
 
@@ -1123,6 +1151,7 @@ weston_wm_window_destroy(struct weston_wm_window *window)
 		xcb_reparent_window(wm->conn, window->id, wm->wm_window, 0, 0);
 		xcb_destroy_window(wm->conn, window->frame_id);
 		weston_wm_window_set_wm_state(window, ICCCM_WITHDRAWN_STATE);
+		weston_wm_window_set_virtual_desktop(window, -1);
 		hash_table_remove(wm->window_hash, window->frame_id);
 		window->frame_id = XCB_WINDOW_NONE;
 	}
@@ -1856,6 +1885,7 @@ weston_wm_get_resources(struct weston_wm *wm)
 		{ "_NET_WM_STATE_FULLSCREEN", F(atom.net_wm_state_fullscreen) },
 		{ "_NET_WM_USER_TIME", F(atom.net_wm_user_time) },
 		{ "_NET_WM_ICON_NAME", F(atom.net_wm_icon_name) },
+		{ "_NET_WM_DESKTOP", F(atom.net_wm_desktop) },
 		{ "_NET_WM_WINDOW_TYPE", F(atom.net_wm_window_type) },
 
 		{ "_NET_WM_WINDOW_TYPE_DESKTOP", F(atom.net_wm_window_type_desktop) },
diff --git a/xwayland/xwayland.h b/xwayland/xwayland.h
index 2bbbac0..a666aeb 100644
--- a/xwayland/xwayland.h
+++ b/xwayland/xwayland.h
@@ -114,6 +114,7 @@ struct weston_wm {
 		xcb_atom_t		 net_wm_state_fullscreen;
 		xcb_atom_t		 net_wm_user_time;
 		xcb_atom_t		 net_wm_icon_name;
+		xcb_atom_t		 net_wm_desktop;
 		xcb_atom_t		 net_wm_window_type;
 		xcb_atom_t		 net_wm_window_type_desktop;
 		xcb_atom_t		 net_wm_window_type_dock;
-- 
2.1.3