Thank you Mary
What I intend to do is extend one of the text input admin settings, then pass in an array of associative array of labels => images, then detect the selected item and put in the text input box which is then passed back to the server on submit in the normal way. This is a medium term implementation, so might be a while to see results, thank you for your help.
I fell asleep last night looking at the file picker issue, far more difficult as passing in a file to the server, looked at the Moodle Forms way and could not find the point where the JavaScript invoked the PHP to parse the file to the server. The rest I think I can do. Is there a MDL tracker for this as a boiler plate core addition would be useful for so many things? Then it could be voted for and get team assistance in it's creation.
Cheers,
Gareth