ewmh: correctly set _NET_ACTIVE_WINDOW

src/ewmh.c

@@ -30,3 +30,15 @@ void ewmh_update_current_desktop() {
                             atoms[_NET_CURRENT_DESKTOP], CARDINAL, 32, 1,
                             &current_desktop);
 }
+
+/*
+ * Updates _NET_ACTIVE_WINDOW with the currently focused window.
+ *
+ * EWMH: The window ID of the currently active window or None if no window has
+ * the focus.
+ *
+ */
+void ewmh_update_active_window(xcb_window_t window) {
+        xcb_change_property(global_conn, XCB_PROP_MODE_REPLACE, root,
+                            atoms[_NET_ACTIVE_WINDOW], WINDOW, 32, 1, &window);
+}

src/mainx.c

@@ -249,6 +249,7 @@ int main(int argc, char *argv[], char *env[]) {
         REQUEST_ATOM(WM_STATE);
         REQUEST_ATOM(WM_CLIENT_LEADER);
         REQUEST_ATOM(_NET_CURRENT_DESKTOP);
+        REQUEST_ATOM(_NET_ACTIVE_WINDOW);
 
         /* TODO: this has to be more beautiful somewhen */
         int major, minor, error;
@@ -412,6 +413,7 @@ int main(int argc, char *argv[], char *env[]) {
         GET_ATOM(WM_STATE);
         GET_ATOM(WM_CLIENT_LEADER);
         GET_ATOM(_NET_CURRENT_DESKTOP);
+        GET_ATOM(_NET_ACTIVE_WINDOW);
 
         xcb_property_set_handler(&prophs, atoms[_NET_WM_WINDOW_TYPE], UINT_MAX, handle_window_type, NULL);
         /* TODO: In order to comply with EWMH, we have to watch _NET_WM_STRUT_PARTIAL */

src/manage.c

@@ -31,6 +31,7 @@
 #include "client.h"
 #include "workspace.h"
 #include "log.h"
+#include "ewmh.h"
 
 /*
  * Go through all existing windows (if the window manager is restarted) and manage them
@@ -450,8 +451,10 @@ map:
                                 if (map_frame)
                                         render_container(conn, new->container);
                         }
-                        if (new->container == CUR_CELL || client_is_floating(new))
+                        if (new->container == CUR_CELL || client_is_floating(new)) {
                                 xcb_set_input_focus(conn, XCB_INPUT_FOCUS_POINTER_ROOT, new->child, XCB_CURRENT_TIME);
+                                ewmh_update_active_window(new->child);
+                        }
                 }
         }
 

src/util.c

@@ -247,6 +247,7 @@ void set_focus(xcb_connection_t *conn, Client *client, bool set_anyways) {
         CLIENT_LOG(client);
         /* Set focus to the entered window, and flush xcb buffer immediately */
         xcb_set_input_focus(conn, XCB_INPUT_FOCUS_POINTER_ROOT, client->child, XCB_CURRENT_TIME);
+        ewmh_update_active_window(client->child);
         //xcb_warp_pointer(conn, XCB_NONE, client->child, 0, 0, 0, 0, 10, 10);
 
         if (client->container != NULL) {