Bug 198904 [DataBinding] Listeners in swt Observables are not removed on dispose
tests/org.eclipse.jface.tests.databinding/src/org/eclipse/jface/tests/internal/databinding/internal/swt/TextObservableValueTest.java
Shell shell = new Shell();
		text = new Text(shell, SWT.NONE);
		
		listener = new ValueChangeEventTracker();
	}
	/**
	 * Asserts that only valid SWT event types are accepted on construction of
	 * TextObservableValue.
	 */
	public void testConstructorUpdateEventTypes() {
		try {
			new TextObservableValue(text, SWT.NONE);
			new TextObservableValue(text, SWT.FocusOut);
			new TextObservableValue(text, SWT.Modify);
			assertTrue(true);
		} catch (IllegalArgumentException e) {
			fail();
		}
		try {
			new TextObservableValue(text, SWT.Verify);
			fail();
		} catch (IllegalArgumentException e) {
			assertTrue(true);
		}
	}
	public void testSetValue() throws Exception {
		TextObservableValue observableValue = new TextObservableValue(text,
				SWT.NONE);
		assertEquals("", observableValue.getValue());
		String value = "value";