Bug 123758 [DataBinding] CComboUpdatableValue Doesn't Handle Text That Isn't in The List of Selected Items
The current implementation of CComboUpdatableValue will only allow setting text if the value is in the list of possible selection values. In reality the CCombo allows either a manually entered value (which may not be in the list) or the selection of a value from the drop down list. I'll be submitting a patch for this shortly.
bundles/org.eclipse.jface.databinding/src/org/eclipse/jface/internal/databinding/swt/CComboUpdatableValue.java
/**
	 * 
	 */
	private final CCombo ccombo;
	private final String attribute;
	private boolean updating = false;
	/**
	 * @param ccombo
	 * @param attribute
	 */
	public CComboUpdatableValue(CCombo ccombo, String attribute) {
		this.ccombo = ccombo;
		this.attribute = attribute;
		if (attribute.equals(ViewersProperties.CONTENT))
			attribute = SWTProperties.TEXT;
		if (attribute.equals(SWTProperties.SELECTION) || 
			attribute.equals(SWTProperties.TEXT)) {
			ccombo.addModifyListener(new ModifyListener() {
				public void modifyText(ModifyEvent e) {
					if (!updating) {
						fireChangeEvent(ChangeEvent.CHANGE, null, null);
					}