Can't select a custom tool type

Our current application being developed in SA3 has required a few custom tool icons.

These have been added to the theme, however there is no way to select these in SA.

The 'type' config parameter is currently a combo box that forces a selection from the list. Perhaps this could be changed to allow free form text entry, so that I can type in the name of the new tool type (as defined in the CSS).

As a workaround, I'm currently using processConfig to manually define the tools array, which has the disadvantage of the tools not appearing in the project inspector.