Name the window manager when one is already running to help debugging sessions issues

2 files changed, 14 insertions, 1 deletions

diff --git a/src/main.c b/src/main.c
index 2a1e6a79a..f6ee50f3e 100644
--- a/src/main.c
+++ b/src/main.c
@@ -587,7 +587,7 @@ main (int argc, char **argv)
     switch (status)
     {
         case -1:
-            g_warning ("Another Window Manager is already running");
+            g_warning ("Could not find a screen to manage, exiting");
             exit (1);
             break;
         case -2:
diff --git a/src/screen.c b/src/screen.c
index 0aca55a9e..40485a0ff 100644
--- a/src/screen.c
+++ b/src/screen.c
@@ -87,12 +87,25 @@ myScreenSetWMAtom (ScreenInfo *screen_info, gboolean replace_wm)
     g_snprintf (selection, sizeof (selection), "WM_S%d", screen_info->screen);
     wm_sn_atom = XInternAtom (display_info->dpy, selection, FALSE);
 
+    XSync (display_info->dpy, FALSE);
     current_wm = XGetSelectionOwner (display_info->dpy, wm_sn_atom);
     if (current_wm)
     {
         if (!replace_wm)
         {
+            const char *wm_name;
+            gchar *display_name;
+
+            display_name = gdk_screen_make_display_name (screen_info->gscr);
+            wm_name = gdk_x11_screen_get_window_manager_name (screen_info->gscr);
+            g_message ("Another Window Manager (%s) is already running on screen %s", wm_name, display_name);
             g_message ("To replace the current window manager, try \"--replace\"");
+            g_free (display_name);
+            /*
+             * Note: gdk_x11_screen_get_window_manager_name() returns a
+             * const not to be freed, no leak here...
+             */
+
             return FALSE;
         }
         gdk_error_trap_push ();