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/ColorCellEditor.java
int ty = (bounds.height - rgbSize.y) / 2;
			if (ty < 0)
				ty = 0;
			colorLabel.setBounds(-1, 0, colorSize.x, colorSize.y);
			rgbLabel.setBounds(
				colorSize.x + GAP - 1, 
				ty, 
				bounds.width - colorSize.x - GAP, 
				bounds.height); 
		}
	}
/**
 * Creates a new color cell editor parented under the given control.
 * The cell editor value is black (<code>RGB(0,0,0)</code>) initially, and has no 
 * validator.
 *
 * @param parent the parent control
 */
public ColorCellEditor(Composite parent) {
	super(parent);
	doSetValue(new RGB(0, 0, 0));
}
/**
 * Creates and returns the color image data for the given control
 * and RGB value. The image's size is either the control's item extent 
 * or the cell editor's default extent, which is 16 pixels square.
 *
 * @param w the control
 * @param color the color
 */