diff --git a/lib/wibox/container/constraint.lua b/lib/wibox/container/constraint.lua
index 4e8a976dc..af0e5594a 100644
--- a/lib/wibox/container/constraint.lua
+++ b/lib/wibox/container/constraint.lua
@@ -7,49 +7,55 @@
 -- @classmod wibox.container.constraint
 ---------------------------------------------------------------------------
 
-local pairs = pairs
-local type = type
 local setmetatable = setmetatable
 local base = require("wibox.widget.base")
+local util = require("awful.util")
 local math = math
 
 local constraint = { mt = {} }
 
 -- Layout a constraint layout
 function constraint:layout(_, width, height)
-    if self.widget then
-        return { base.place_widget_at(self.widget, 0, 0, width, height) }
+    if self._private.widget then
+        return { base.place_widget_at(self._private.widget, 0, 0, width, height) }
     end
 end
 
 -- Fit a constraint layout into the given space
 function constraint:fit(context, width, height)
     local w, h
-    if self.widget then
-        w = self._strategy(width, self._width)
-        h = self._strategy(height, self._height)
+    if self._private.widget then
+        w = self._private.strategy(width, self._private.width)
+        h = self._private.strategy(height, self._private.height)
 
-        w, h = base.fit_widget(self, context, self.widget, w, h)
+        w, h = base.fit_widget(self, context, self._private.widget, w, h)
     else
         w, h = 0, 0
     end
 
-    w = self._strategy(w, self._width)
-    h = self._strategy(h, self._height)
+    w = self._private.strategy(w, self._private.width)
+    h = self._private.strategy(h, self._private.height)
 
     return w, h
 end
 
---- Set the widget that this layout adds a constraint on.
+--- The widget to be constrained.
+-- @property widget
+-- @tparam widget widget The widget
+
 function constraint:set_widget(widget)
-    self.widget = widget
+    self._private.widget = widget
     self:emit_signal("widget::layout_changed")
 end
 
+function constraint:get_widget()
+    return self._private.widget
+end
+
 --- Get the number of children element
 -- @treturn table The children
 function constraint:get_children()
-    return {self.widget}
+    return {self._private.widget}
 end
 
 --- Replace the layout children
@@ -61,6 +67,8 @@ end
 
 --- Set the strategy to use for the constraining. Valid values are 'max',
 -- 'min' or 'exact'. Throws an error on invalid values.
+-- @property strategy
+
 function constraint:set_strategy(val)
     local func = {
         min = function(real_size, limit)
@@ -78,27 +86,45 @@ function constraint:set_strategy(val)
         error("Invalid strategy for constraint layout: " .. tostring(val))
     end
 
-    self._strategy = func[val]
+    self._private.strategy = func[val]
     self:emit_signal("widget::layout_changed")
 end
 
+function constraint:get_strategy()
+    return self._private.strategy
+end
+
 --- Set the maximum width to val. nil for no width limit.
+-- @property height
+-- @param number
+
 function constraint:set_width(val)
-    self._width = val
+    self._private.width = val
     self:emit_signal("widget::layout_changed")
 end
 
+function constraint:get_width()
+    return self._private.width
+end
+
 --- Set the maximum height to val. nil for no height limit.
+-- @property width
+-- @param number
+
 function constraint:set_height(val)
-    self._height = val
+    self._private.height = val
     self:emit_signal("widget::layout_changed")
 end
 
+function constraint:get_height()
+    return self._private.height
+end
+
 --- Reset this layout. The widget will be unreferenced, strategy set to "max"
 -- and the constraints set to nil.
 function constraint:reset()
-    self._width = nil
-    self._height = nil
+    self._private.width = nil
+    self._private.height = nil
     self:set_strategy("max")
     self:set_widget(nil)
 end
@@ -117,13 +143,9 @@ end
 -- @treturn table A new constraint container
 -- @function wibox.container.constraint
 local function new(widget, strategy, width, height)
-    local ret = base.make_widget()
+    local ret = base.make_widget(nil, nil, {enable_properties = true})
 
-    for k, v in pairs(constraint) do
-        if type(v) == "function" then
-            ret[k] = v
-        end
-    end
+    util.table.crush(ret, constraint, true)
 
     ret:set_strategy(strategy or "max")
     ret:set_width(width)
@@ -140,6 +162,10 @@ function constraint.mt:__call(...)
     return new(...)
 end
 
+--@DOC_widget_COMMON@
+
+--@DOC_object_COMMON@
+
 return setmetatable(constraint, constraint.mt)
 
 -- vim: filetype=lua:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:textwidth=80