Customizing the yahoo astra tree

hi

I found the ASTRA components (http://www.yahooapis.com/flash/astra-flash/tree/) , and they are great, but i want to customize them, and i dont know how. in the examples the use this this code:

mytree.setRendererStyle(“closedBranchIcon”, folderClosedIcon);
mytree.setRendererStyle(“openBranchIcon”, folderOpenIcon);
mytree.setRendererStyle(“leafIcon”, fileIcon);

where can i get a list of the “codes” i can use like “closedBranchIcon” or “openBranchIcon”?

for example i would like to remove the frame that surrounds the tree, haw can i do that?