Arrow-based Scrolling with Hidden Items is Broken

Hi all I'm still having the problem I reported in "Arrow Keys do not Work as Expected" -- over the course of using the beta through various versions, all with the same issue, I've worked out how to replicate it:

starting with a fresh 'stream' of tweets:

1. starting at the newest item, click on the item, then scroll down with the down-arrow key, which should mark items as read

2. stop reading before the end of your un-read tweets. 'clear' already-read tweets with 'Hide seen' button

3. by now, some new tweets have come in. start reading behavior again at the first new tweet

4. You should find that at the point where there are 'hidden' tweets (right now for me, after the tweet that is 7m old and before the tweet that is 1h old).

--> Instead of jumping to the 1h-old tweet, the down-arrow now just moves the scrollbar.

5. Try to start again by clicking on the 1h-old tweet. It gets marked as 'read'.

--> Now you will find that the down-arrow key causes a big jump in scrolling. In some cases, this leads to the 'blank' screen as you've now scrolled to the very end of your visible tweet queue.

so to mark the rest of the tweets as read I have to click on each individually (or click on the newest one read, scroll down to the oldest one read, and shift-click --> NICE!)

tim