Comment 19 for bug 89381

Rather than patching firefox as well as every other ubuntu program that might open an image, I think this fonctionality would better be implemented as a patch to the GtkFileChooser itself. GtkFileChooser should look in a config file for a default preview widget, and use it if no other preview widget has been defined by the calling program.

Ubuntu could use the nautilus preview widget as a system-wide default, Xubuntu would use a Thunar preview widget, and so on. Therefore you would have preview functionality when opening files from any programs (not only for images, but also for pdf files, text files, etc), and said programs could always overwrite the defaults and provide their own widget if they need it.

I believe this is more or less the way windows does it, by the way: whenever you are in a file open dialog you seem to be able to do everything you can do in the file manager. Windows XP has it, and I think it even dates back to windows 95... too bad the picture preview feature always gets delayed in linux desktop environments, because of philosophical discussions about how much a file open dialog should do.