ftp get from a Tkinter gui: advice wanted

[Russell E. Owen]

I'm writing a Tkinter app (telescope remote controller). The application 
presently runs on unix and MacOS X and I think some users will want to 
use Windows. It's going just fine, but I'm trying to add the ability to 
automatically get images via binary ftp (i.e. as each image is recorded) 
and am realizing it's harder than I though.

Ideally, I'd like image download to work like a typical web browser 
download: a status window that shows each transfer, how far along it is, 
allows the user to cancel it, etc.

This sounds messy to write, though I'll certainly do it if it comes to 
that. So I'm asking for advice before diving in -- especially as I hate 
to reinvent the wheel.

I'm hoping somebody has either written such a beast already (in Tkinter 
or Tk), but a Google search hasn't turned up anything yet. Anybody have 
any hints where to look?

I'd also be fairly happy to have a web browser to do the download (it's 
not perfect -- one loses the ability to automatically put the files in 
the right place -- but it'd do). However, my attempts to use the 
webbrowser module for this on MacOS X are not working. I have unix 
command-line 2.2.2 and aqua framework 2.3 both installed. Neither 
actually ever calls my web browser when I supply the ftp link. The unix 
version does try to download the file (with no feedback) and ends up 
downloading an empty file with no feedback (not much use). The latter 
reliably hangs the Finder (I'm about to file a bug report).

Any advice or suggestions would be very much appreciated.

-- Russell