fix: set button foreground widget

The old code mixed up a variable such that set_foreground() would set
the foreground to the same widget it used to be, instead of using the
new widget provided by the caller.  This made it impossible to
dynamically change the foreground.

glooey/buttons.py

@@ -303,7 +303,7 @@ def set_foreground(self, widget):
         if self._foreground is not None:
             self._detach_child(self._foreground)
 
-        self._attach_child(self._foreground)
+        self._attach_child(widget)
         self._foreground = widget
         self._repack_and_regroup_children()
 

tests/buttons/demo_button.py

@@ -60,6 +60,9 @@ def test_button():
     yield "Grey inactive button (no rollover)."
     button.enable()
 
+    button.foreground = TestLabel("Different foreground widget")
+    yield "Replace the foreground widget."
+
     button.set_background(
             base_top    = pyglet.image.load('assets/64x4/green.png'),
             base_bottom = pyglet.image.load('assets/64x4/green.png'),
@@ -82,22 +85,22 @@ def test_button():
     button = TestButton('Constructor text')
     button.push_handlers(on_click, on_double_click)
     gui.clear(); gui.add(button)
-    yield "Different button text."
+    yield "Set text via constructor."
 
     button = TestButtonNoForeground()
     button.push_handlers(on_click, on_double_click)
     gui.clear(); gui.add(button)
-    yield "No button text."
+    yield "No foreground."
 
     button = TestButtonCustomAttrIntrospection("Custom attribute introspection")
     button.push_handlers(on_click, on_double_click)
     gui.clear(); gui.add(button)
-    yield "Custom attribute introspection (same appearance as before)"
+    yield "Custom attribute introspection (same appearance as first test)"
 
     button = TestButtonSuperclassIntrospection("Superclass introspection")
     button.push_handlers(on_click, on_double_click)
     gui.clear(); gui.add(button)
-    yield "Superclass introspection (same appearance as before)"
+    yield "Superclass introspection (same appearance as first test)"
 
 
 pyglet.app.run()