[horde] Left menu loading with IE

[Chuck Hagenbuch]

Quoting Bill Graham <grahamcw at hurleybulldogs.com>:

> Recently the left menu loading time has become extreme with EI 6 over https.
> Every time the left menu refreshes it loads down some 260 images - and even
> with a broadband connection, it  take some time and pretty much stops the app
> from being useful while it loads.

Turn off the alpha_filter preference (it's off by default now).

-chuck

-- 
"But she goes not abroad in search of monsters to destroy." - John 
Quincy Adams