I have not been able to get the new Launcher to work %100 behind a proxy (squid3.1) .

There are no problems if I disable my (linux) firewall..
Windows XP firewall is completely disabled (as I'm on a LAN).

But with (linux) firewall enabled it appears authentication is failing .. the authentication does not seem to be hitting the proxy (no log entries)..

As work around I have opened up the following IPs in my firewall..
MINE_IPS="207.171.189.80 207.171.185.200 207.171.187.117"
MINE_IPS="$MINE_IPS 184.72.181.155"
MINE_IPS="$MINE_IPS 23.22.108.65 23.23.71.207 23.23.54.17 23.23.133.220 "
MINE_IPS="$MINE_IPS 66.6.40.24 23.22.108.65 174.129.49.31 50.17.182.192"
MINE_IPS="$MINE_IPS 54.242.84.215 54.236.153.6 54.234.88.167 54.236.165.164 54.243.73.214"
MINE_IPS="$MINE_IPS 107.20.203.89 184.72.237.108 107.20.203.89"

But every day I seem to have to add a few more IPs so its not a long term solution...

I'm using the following command to start the laucher..
java -Dhttps.proxyHost=xxx -Dhttps.proxyPort=xxx -Dhttp.proxyHost=xxx -Dhttp.proxyPort=xxx -Dproxy.User=xxx -Dhttp.proxyPassword=xxx -Xmx800m -jar Minecraft.1.6.jar
(see attachment mc-proxy-err-jvm-options.txt)

Ive also tried the "minecraft" proxy args..
--proxyUser, --proxyPass, --proxyHost, --proxyPort
But these settings wont even allow the "Update Notes" tab content to download.. Actually the laucher seems to hang ..
(see attachment mc-proxy-err-mc-options.txt)

Hope this enough info..