I'm looking at the dock skin CSS files, and they all set the padding for the dock zone to 4px 0 0 4px. Next, they set padding-right to 4px in a way that is apparently (according to the comments) hidden from IE6.
BUT, if you look at the dock.css file that appears in the install folder under skins, the last line is:
padding: 4px !important;
Doesn't this force the padding for the entire dock zone to 4px regardless of what you put in the skin's CSS file? (I'm assuming, of course, that you're not overriding the setting via a selector for #dockzoneid.)
I've tested this by altering these settings in my skin's CSS file and don't see any affect, though I know that things are a little complex in there, so I wanted to verify this.
I'm suspecting these were settings that were left over from earlier implementations, and that the setting of this to 4px was to fix something with scroll bars.
Can you confirm?