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
* @return <code>true</code> if the value is valid, and <code>false</code>
 *  if invalid
 *
 * @see #setValueValid
 */
public boolean isValueValid() {
	return valid;
}
/**
 * Processes a key release event that occurred in this cell editor.
 * <p>
 * The default implementation of this framework method interprets
 * the ESC key as canceling editing, and the RETURN key
 * as applying the current value. Subclasses should call this method
 * at appropriate times. Subclasses may also extend or reimplement.
 * </p>
 *
 * @param keyEvent the key event
 */
protected void keyReleaseOccured(KeyEvent keyEvent) {
	if (keyEvent.character == '\u001b') { 
		fireCancelEditor();
		return;
	} else if (keyEvent.character == '\r') { 
		fireApplyEditorValue();
		return;
	}
}
/**
 * Performs the copy action.