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
public Point computeSize(
			Composite editor, 
			int wHint, 
			int hHint, 
			boolean force) {
			if (wHint != SWT.DEFAULT && hHint != SWT.DEFAULT)
				return new Point(wHint, hHint);
			Point colorSize = colorLabel.computeSize(SWT.DEFAULT, SWT.DEFAULT, force);
			Point rgbSize = rgbLabel.computeSize(SWT.DEFAULT, SWT.DEFAULT, force);
			return new Point(
				colorSize.x + GAP + rgbSize.x, 
				Math.max(colorSize.y, rgbSize.y)); 
		}
		public void layout(Composite editor, boolean force) {
			Rectangle bounds = editor.getClientArea();
			Point colorSize = colorLabel.computeSize(SWT.DEFAULT, SWT.DEFAULT, force);
			Point rgbSize = rgbLabel.computeSize(SWT.DEFAULT, SWT.DEFAULT, force);