Bugfix: Also fix horizontal resizing

The same problem as in the commit before this one was present. Additionally,
the dock_clients and internal bar were not taken into account everywhere.

src/workspace.c

@@ -417,3 +417,31 @@ void workspace_update_urgent_flag(Workspace *ws) {
 
         ws->urgent = false;
 }
+
+/*
+ * Returns the width of the workspace.
+ *
+ */
+int workspace_width(Workspace *ws) {
+        return ws->rect.width;
+}
+
+/*
+ * Returns the effective height of the workspace (without the internal bar and
+ * without dock clients).
+ *
+ */
+int workspace_height(Workspace *ws) {
+        int height = ws->rect.height;
+        i3Font *font = load_font(global_conn, config.font);
+
+        /* Reserve space for dock clients */
+        Client *client;
+        SLIST_FOREACH(client, &(ws->screen->dock_clients), dock_clients)
+                height -= client->desired_height;
+
+        /* Space for the internal bar */
+        height -= (font->height + 6);
+
+        return height;
+}