Bug 176882 [DataBinding] Create SWTObservables.observeEditable(...)
We need to provide an observable for the editable property of Text.
tests/org.eclipse.jface.tests.databinding/src/org/eclipse/jface/tests/databinding/swt/SWTObservablesTest.java
List list = new List(shell, SWT.NONE);
		IObservableList observableList = SWTObservables.observeItems(list);
		assertNotNull(observableList);
		assertTrue(observableList instanceof ListObservableList);
	}
	public void testObserveItemsOfUnsupportedControl() throws Exception {
		Table table = new Table(shell, SWT.NONE);
		try {
			SWTObservables.observeItems(table);
			fail("Exception should have been thrown");
		} catch (IllegalArgumentException e) {
		}
	}
	public void testObserveSingleSelectionIndexOfTable() throws Exception {
		Table table = new Table(shell, SWT.NONE);
		ISWTObservableValue value = SWTObservables
				.observeSingleSelectionIndex(table);
		assertNotNull(value);
		assertTrue(value instanceof TableObservableValue);
		TableObservableValue tableObservable = (TableObservableValue) value;
		assertEquals(SWTProperties.SELECTION, tableObservable.getAttribute());
	}
	public void testObserveSingleSelectionIndexOfUnsupportedControl()
			throws Exception {
		List list = new List(shell, SWT.NONE);
		try {
			SWTObservables.observeSingleSelectionIndex(list);
			fail("Exception should have been thrown");
		} catch (IllegalArgumentException e) {
		}