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/ComboObservableValue.java
private final Combo combo;
	private final String attribute;
	private boolean updating = false;
	private String currentValue;
	/**
	 * @param combo
	 * @param attribute
	 */
	public ComboObservableValue(Combo combo, String attribute) {
		super(combo);
		this.combo = combo;
		this.attribute = attribute;
		
		if (attribute.equals(SWTProperties.SELECTION)
				|| attribute.equals(SWTProperties.TEXT)) {
			this.currentValue = combo.getText();
			combo.addModifyListener(new ModifyListener() {
				public void modifyText(ModifyEvent e) {
					if (!updating) {
						String oldValue = currentValue;
						currentValue = ComboObservableValue.this.combo
								.getText();