add simple example on how to subclass RectItem for customization

examples/customrectitemconfig.py

@@ -0,0 +1,26 @@
+from PyQt4.QtGui import QPen
+from PyQt4.Qt import Qt
+from sloth.items import RectItem
+
+
+class CustomRectItem(RectItem):
+    # display values of x and y as text inside the rectangle
+    defaultAutoTextKeys = ['x', 'y']
+
+    def __init__(self, *args, **kwargs):
+        RectItem.__init__(self, *args, **kwargs)
+
+        # set drawing pen to red with width 2
+        self.setPen(QPen(Qt.red, 2))
+
+LABELS = (
+    {
+        'attributes': {
+            'class':      'rect',
+        },
+        'inserter': 'sloth.items.RectItemInserter',
+        'item':     CustomRectItem,  # use custom rect item instead of sloth's standard item
+        'text':     'Rectangle',
+    },
+)
+