Fix: Some properties on the window created are now set in here, to make it work problerly inside a tinyMCE-popupwindow.
Paths to all javascripts are now absolute.
This is the javascript function to use in the 'filebrowser_callback' option when setting up tinyMCE.
Adapt this function with the settings you need, often just the urls that provides data for the tree and the data-display.