Make 'weak' the default for Component hug preferences.

We can revisit this once Components have a more robust way of supplying
their size preferences.

enable/coordinate_box.py

@@ -97,10 +97,10 @@ class CoordinateBox(HasTraits):
     layout_size_hint = Tuple(0.0, 0.0)
 
     # How strongly a layout box hugs it's width hint.
-    hug_width = ConstraintPolicyEnum('strong')
+    hug_width = ConstraintPolicyEnum('weak')
 
     # How strongly a layout box hugs it's height hint.
-    hug_height = ConstraintPolicyEnum('strong')
+    hug_height = ConstraintPolicyEnum('weak')
 
     # How strongly a layout box resists clipping its contents.
     resist_width = ConstraintPolicyEnum('strong')

examples/enable/constraints_demo.py

@@ -43,22 +43,20 @@ class Demo(HasTraits):
     def _canvas_default(self):
         parent = ConstraintsContainer(bounds=(500,500), padding=20)
 
-        hugs = {'hug_width':'weak', 'hug_height':'weak'}
-        one = Component(id="r", bgcolor=0xFF0000, **hugs)
-        two = Component(id="g", bgcolor=0x00FF00, **hugs)
-        three = Component(id="b", bgcolor=0x0000FF, **hugs)
+        one = Component(id="r", bgcolor=0xFF0000)
+        two = Component(id="g", bgcolor=0x00FF00)
+        three = Component(id="b", bgcolor=0x0000FF)
 
         parent.add(one, two, three, self.child_canvas)
         return parent
 
     def _child_canvas_default(self):
         parent = ConstraintsContainer(id="child", share_layout=self.share_layout)
 
-        hugs = {'hug_width':'weak', 'hug_height':'weak'}
-        one = Component(id="c", bgcolor=0x00FFFF, **hugs)
-        two = Component(id="m", bgcolor=0xFF00FF, **hugs)
-        three = Component(id="y", bgcolor=0xFFFF00, **hugs)
-        four = Component(id="k", bgcolor=0x000000, **hugs)
+        one = Component(id="c", bgcolor=0x00FFFF)
+        two = Component(id="m", bgcolor=0xFF00FF)
+        three = Component(id="y", bgcolor=0xFFFF00)
+        four = Component(id="k", bgcolor=0x000000)
 
         parent.add(one, two, three, four)
         return parent
@@ -80,7 +78,6 @@ def _constraints_def_changed(self):
         y = components[2]
         k = components[3]
 
-
         try:
             new_cns = eval(self.constraints_def)
         except Exception, ex: