diff --git a/box.lua b/box.lua
index 3f7fe62..03e2a95 100644
--- a/box.lua
+++ b/box.lua
@@ -10,10 +10,16 @@ local function new(args)
   args.arrow_type = base.arrow_type.NONE
 
   local ret = context(args)
---   placement.centered (ret.wibox)
---   ret.wibox:set_valign("center")
---   ret.wibox:set_halign("center")
-  ret.wibox:set_shape (shape.rounded_rect, 10)
+
+  local w = ret.wibox
+
+  w:set_shape (shape.rounded_rect, 10)
+
+  local function f() placement.centered(w) end
+
+  w:connect_signal("property::width" ,f)
+  w:connect_signal("property::height",f)
+  f()
 
   return ret
 end
diff --git a/smart_wibox.lua b/smart_wibox.lua
index 8a0342a..88e51f2 100644
--- a/smart_wibox.lua
+++ b/smart_wibox.lua
@@ -165,6 +165,8 @@ end
 -- @param use_mouse Use the mouse position instead of the widget center as
 -- reference point.
 function wb_func:move_by_parent(geo, use_mouse)
+    if rawget(self, "is_relative") == false then return end
+
     local dps = placement.get_relative_points(geo, mode)
 
     rawset(self, "possible_positions", dps)
@@ -184,6 +186,12 @@ function wb_func:set_hoffset(offset)
     
 end
 
+--- Set if the wibox take into account the other wiboxes.
+-- @tparam boolean val Take the other wiboxes position into account
+function wb_func:set_relative(val)
+    rawset(self, "is_relative", val)
+end
+
 --- A brilliant idea to totally turn the whole hierarchy on its head
 -- and create a widget that own a wibox...
 local function create_auto_resize_widget(self, wdg, args)
@@ -225,6 +233,10 @@ local function create_auto_resize_widget(self, wdg, args)
         w:set_shape(args.shape, unpack(args.shape_args or {}))
     end
 
+    if args.relative ~= nil then
+        w:set_relative(args.relative)
+    end
+
     for k,v in ipairs{"shape_border_color", "shape_border_width"} do
         if args[v] then
             w["set_"..v](w, args[v])