Add a preview widget to "Open..." and "Save..." dialogs.
Especially when selecting files to upload ("Open..."), it's really necessary to have a preview thumbnail.
I often find myself using three separate programs to achieve the task of uploading an image: First I need a file browser to navigate to the correct folder to open a previewer, then I use the previewer to search for the correct image and get the filename to tell epiphany to upload, then I navigate through the filechooser in epiphany to the correct file.
Attached is an attempt at resolving this (adapted from firefox's implementation).
So far, I have only been able to get previews in the "Save..." dialog; not sure why this isn't working for "Open..."