I see this as similar to the attachment interface in DIMP (which I 
really like) in terms of the functionality lost, but not quite as 
streamlined UI-wise. I don't think it's worth the tradeoff. It 
actually applied with just some fuzzy offsets to HEAD, though, so nice 
work on that, and some people may well prefer it - you might want to 
put the patch on the wiki with other contributed modifications.

Many of my customers were confused by the IMP attachment handling so

I've done some UI revisions to the message composition screen.



In the current UI, the attachment "button" in compose options doesn't

take any obvious action -- my end users were expecting a popup like the

"address book" or "special characters" options. And the esoteric

attachment options (e.g. "attachment" vs "inline" disposition and

attachment description) are confusing to users who have come from other

webmail services.



I simplified this by removing attachment button, relocating the message

attachment section just above the message body, and removing the

extraneous options to keep the UI clean. Also, I changed the units of

Max Attachment Size to MB -- bytes didn't make a lotta sense here. 
I've got a screenshot of the changes here:



   http://ic.ucsb.edu/~matthewdunham/misc/compose_screenshot.png



If these are acceptable I'd love to see them integrated into the trunk.

I've included patches (to 4.3), but these could maybe use a bit of

review to ensure they're properly Horde-ified.