Properties are values attached to instances of your widgets. A property is identified by a 32-bit ID and its value is the width of a pointer.

Each widget instance may have a property or not have it. When you set a property on a widget for the first time, the property is added to the widget; it then stays there for the life of the widget.

Some property IDs are predefined by the widget package; you can make up your own property IDs as well.

xpProperty_Refcon"0" A window's refcon is an opaque value used by client code to find other data based on it.
xpProperty_Dragging"1" These properties are used by the utilities to implement dragging.
xpProperty_Hilited"4" Is the widget highlighted? (For widgets that support this kind of thing.)
xpProperty_Object"5" Is there a C++ object attached to this widget?
xpProperty_Clip"6" If this property is 1, the widget package will use OpenGL to restrict drawing to the Widget's exposed rectangle.
xpProperty_Enabled"7" Is this widget enabled (for those that have a disabled state too)?
xpProperty_UserStart"10000" NOTE: Property IDs 1 - 999 are reserved for the widgets library.

NOTE: Property IDs 1000 - 9999 are allocated to the standard widget classes provided with the library.

Properties 1000 - 1099 are for widget class 0, 1100 - 1199 for widget class 1, etc.