Bug 198904 [DataBinding] Listeners in swt Observables are not removed on dispose
bundles/org.eclipse.jface.databinding/src/org/eclipse/jface/internal/databinding/internal/swt/ButtonObservableValue.java
selectionValue = button.getSelection();
			fireValueChange(Diffs.createValueDiff(oldSelectionValue ? Boolean.TRUE : Boolean.FALSE,
					selectionValue ? Boolean.TRUE : Boolean.FALSE));
		}
	};
	/**
	 * @param button
	 */
	public ButtonObservableValue(Button button) {
		super(button);
		this.button = button;
		button.addListener(SWT.Selection, updateListener);
		button.addListener(SWT.DefaultSelection, updateListener);
	}
	public void doSetValue(final Object value) {
		boolean oldSelectionValue = selectionValue;
		selectionValue = value == null ? false : ((Boolean) value)
				.booleanValue();
		button.setSelection(selectionValue);
		fireValueChange(Diffs.createValueDiff(oldSelectionValue ? Boolean.TRUE : Boolean.FALSE,
				selectionValue ? Boolean.TRUE : Boolean.FALSE));
	}
	public Object doGetValue() {
		return button.getSelection() ? Boolean.TRUE : Boolean.FALSE;
	}
	public Object getValueType() {
		return Boolean.class;
	}
}