Bug 12329 [Cell Editors] Request:ComboBoxCellEditor READ_ONLY style
Although CCombo accepts SWT.READ_ONLY style, there is no way to specify style when it is used in ComboBoxCellEditor. How about adding createControl(Composite parent, int style) method to ComboBoxCellEditor class?
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/CellEditor.java
/**
	 * List of cell editor listeners (element type: <code>ICellEditorListener</code>).
	 */
	private ListenerList listeners = new ListenerList(3);
	/**
	 * List of cell editor property change listeners 
	 * (element type: <code>IPropertyChangeListener</code>).
	 */
	private ListenerList propertyChangeListeners = new ListenerList(3);