[horde] imp: missing scrollbar

[Andreas Schulze]

Erling Preben Hansen:

> If I zoom out under 100 % like to 90% the scroolbar disapers. (google
> chrome and firefox)
> It comes back when I zoom in again.

What a hint!
The scroll bar goes away and come back again when I zoom in and out.

There are three scroll bars visible:
  1.) imap folder list
  2.) message list
  3.) message preview

1 and 3 are native gui elements depending on the window manager.
2 looks different. I assume it's created with Javascript and behave  
different for that reason.

Andreas