List all tags in <title> when URL is /tag/foo bar/

I just updated from UTW to WP2.3-Tagging with SimpleTags but there seems to be no way to get what UTW_ShowCurrentTagSet() did.

Unfortunatelly the wp_title() or (the same) single_tag_title() only outputs one tag.

Like URL /tag/foo/ gives the output foo.
But URL /tag/foo+bar/ also gives only foo.

So right now there seems to be no propper replacement for UTW_ShowCurrentTagSet

Any ideas?

PS:
The problem is also described here https://www.ads-software.com/support/topic/136356#post-686488 and here https://www.lifespy.com/2007/how-to-switch-from-ultimate-tag-warrior-to-wordpress-23-tagging/#comment-118283