I just tried this at on Safari (Version 6.0.4 (8536.29.13) as checked in Safari > About Safari) on a Mac running OS X 10.8.3. I visited http://www.sencha.com/examples/#Exam...:duallistfield and followed these steps:
* Open the example
* Click on an item - verify it was selected
* Hold the cmd key (ctrl on a non-mac) and click another item, verify that two items are selected
* Release the key and drag the items - verify that the status says "2 items selected"
* Drop the items on the other side - verify that there are two new items on the other side
* Repeat with the shift key (consistent cross-OS) - verify that all items between the first and second click are selected (may be more than two items)
Can you verify that this is working correctly, and if not, at which step it isn't working?
Interesting - this was a bug report from one of my coworkers, and he was able to reproduce this in front of me yesterday. However, on my own Mac running Safari 6.0.5 and OS X 10.8.4, the application works perfectly as intended!
I will confer with my coworker when he arrives today, but perhaps this is a configuration issue on his machine, rather than an issue with the GXT framework.