Comment 4 for bug 613886

@Pedro, I am reopening this as a bug, something is wrong when having Flash can intercepta standard OS file dialog.

I can confirm this same problem in Maverick using the latest Adobe Flash for 64-bit.

This seems to be website-specific. Try to upload an image to Flickr with Flash enabled - no preview. Try to upload an image to your Launchpad profile with Flash enabled - preview is OK. It looks like websites can override the OS upload dialog with their own or something along those lines.