Bug 176882 [DataBinding] Create SWTObservables.observeEditable(...)
We need to provide an observable for the editable property of Text.
bundles/org.eclipse.jface.databinding/src/org/eclipse/jface/databinding/swt/SWTObservables.java
* </ul>
	 * 
	 * @param control
	 * @return observable value
	 * @throws IllegalArgumentException
	 *             if <code>control</code> type is unsupported
	 */
	public static ISWTObservableValue observeMin(Control control) {
		if (control instanceof Spinner) {
			return new SpinnerObservableValue((Spinner) control,
					SWTProperties.MIN);
		} else if (control instanceof Scale) {
			return new ScaleObservableValue((Scale) control, SWTProperties.MIN);
		}
		throw new IllegalArgumentException(
				"Widget [" + control.getClass().getName() + "] is not supported."); 
	}
	/**
	 * Returns an observable observing the maximum attribute of the provided
	 * <code>control</code>. The supported types are:
	 * <ul>
	 * <li>org.eclipse.swt.widgets.Spinner</li>
	 * <li>org.eclipse.swt.widgets.Scale</li>
	 * </ul>
	 * 
	 * @param control
	 * @return observable value
	 * @throws IllegalArgumentException
	 *             if <code>control</code> type is unsupported
	 */