Hi,

Unfortunately i didn't found any way to do that with the standard "Symbolic IO field".

The only way to do it is to use it a CWC (custom web control), if you need an example of CWC i can help you with that, i've started a GitHub where i'm uploading some custom web control to share with other programmers.

You can find the "Select" element that have the same function as the Symbolic IO field but you can populate the drop down list with any type of element, of course the graphic style is different but you can edit the HTML code or ad some CSS to change the graphic behavior

Here the Link