Support _NET_WM_VISIBLE_NAME. As per specification this is necessary since we can display custom titles with title_format.

fixes #1872

include/atoms.xmacro

@@ -1,6 +1,7 @@
 xmacro(_NET_SUPPORTED)
 xmacro(_NET_SUPPORTING_WM_CHECK)
 xmacro(_NET_WM_NAME)
+xmacro(_NET_WM_VISIBLE_NAME)
 xmacro(_NET_WM_MOVERESIZE)
 xmacro(_NET_WM_STATE_FULLSCREEN)
 xmacro(_NET_WM_STATE_DEMANDS_ATTENTION)

include/ewmh.h

@@ -45,6 +45,12 @@ void ewmh_update_desktop_viewport(void);
  */
 void ewmh_update_active_window(xcb_window_t window);
 
+/**
+ * Updates _NET_WM_VISIBLE_NAME.
+ *
+ */
+void ewmh_update_visible_name(xcb_window_t window, const char *name);
+
 /**
  * Updates the _NET_CLIENT_LIST hint. Used for window listers.
  */

include/window.h

@@ -81,3 +81,10 @@ void window_update_hints(i3Window *win, xcb_get_property_reply_t *prop, bool *ur
  *
  */
 void window_update_motif_hints(i3Window *win, xcb_get_property_reply_t *prop, border_style_t *motif_border_style);
+
+/**
+ * Returns the window title considering the current title format.
+ * If no format is set, this will simply return the window's name.
+ *
+ */
+i3String *window_parse_title_format(i3Window *win);