Only arrange screen for non-floating wiboxes

Floating wiboxes dont influence client's position and thus no arrange
is necessary.

Signed-off-by: Uli Schlachter <psychon@znc.in>

wibox.c

@@ -331,6 +331,10 @@ wibox_position_update(wibox_t *wibox)
     if (wibox->screen == SCREEN_UNDEF)
         return;
 
+    /* If this is a non-floating wibox, it limits the space available to clients
+     * and thus clients need to be repositioned.
+     */
+    if (wibox->position != Floating)
         globalconf.screens[wibox->screen].need_arrange = true;
 
     /* Place wibox'es at the edge of the screen, struts come later. */