When using drag-and-drop HTML5 uploading, attempts to drag files from Konqueror or Nautilus to Firefox or Chrome/Chromium work perfectly, but attempts to drag files from PCManFM either only work sometimes (Chrome) or open the file as if the site hadn't requested to handle drag-and-drop (Firefox).
Version: PCManFM 0.9.9 as distributed with Lubuntu 11.10 (Oneiric Ocelot).
Steps to reproduce:
1. Create some trivial, pointless file. (Or use the attached one)
2. Open Firefox or Chrome and navigate to http://www.mediafire.com/ (no account required)
3. Open PCManFM
4. Drag the trivial, pointless file onto the folder graphic in the browser.
5. Watch as the browser displays or offers a download of the file (Firefox) or sometimes ignores the drag-and-drop (Chrome).
6. Repeat with Konqueror or Nautilus and watch as the MediaFire upload manager kicks into action every time.