populating dropdownlist in ScripUI

I was shown how to poplate the .name value of an AVlayer selection in to a drop down list with this method.

var userSelection = app.project.activeItem.selectedLayers;

var selectionNames = [];

for (var j=0; j<userSelection.length; j++) selectionNames[j] = userSelection[j].name;

var dd = groupOne.add("dropdownlist", undefined, selectionNames);

However I'm trying to write this as a dockable script and the syntax appears to be differnt.

For my DD I have the following.

myDropDownList: DropDownList{properties:{items:['DD item1', 'DD item 2', 'DD item 3']}},\

I've tried replaing the array above with the selectionNames variable but have had no luck. I feel it must be a syntax issue but have been unable to find enough detailed information in the pdf. I've looked at other scripts but I'm getting lost in the code (pretty new to javascript). Any tips?