Found issue in ImageBrowser.php, for thumbnail, getThumbnail uses setImageHeaders, which send whole image size, not thumbnail size, causing thumbnail loading delay or fail (depending on browser)
I've been playing around with the ImageBrowser (Editor) and would love to see a variation of the ImageBrowser as a standalone widget. If I could use it without the Editor to simply select or upload an image file that would really add value to some of my applications (for which I now have to use a different tool: elFinder). Since the ImageBrowser already exists, hopefully this would be an easy addition to the KendoUI toolset! :)