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/DialogCellEditor.java
static {
		ImageRegistry reg = JFaceResources.getImageRegistry();
		reg.put(CELL_EDITOR_IMG_DOTS_BUTTON, ImageDescriptor.createFromFile(DialogCellEditor.class, "images/dots_button.gif"));
	}
	/**
	 * Internal class for laying out the dialog.
	 */
	private class DialogCellLayout extends Layout {
		public void layout(Composite editor, boolean force) {
			Rectangle bounds = editor.getClientArea();
			Point size = button.computeSize(SWT.DEFAULT, SWT.DEFAULT, force);
			if (contents != null)
				contents.setBounds(0, 0, bounds.width-size.x, bounds.height);
			button.setBounds(bounds.width-size.x, 0, size.x, bounds.height);
		}
		public Point computeSize(Composite editor, int wHint, int hHint, boolean force) {
			if (wHint != SWT.DEFAULT && hHint != SWT.DEFAULT)
				return new Point(wHint, hHint);
			Point contentsSize = contents.computeSize(SWT.DEFAULT, SWT.DEFAULT, force); 
			Point buttonSize =  button.computeSize(SWT.DEFAULT, SWT.DEFAULT, force);
			
			
			
			Point result = new Point(buttonSize.x,
							        Math.max(contentsSize.y, buttonSize.y));
			return result;			
		}
	}
/**
 * Creates a new dialog cell editor parented under the given control.