Version:           1.7.1 (using KDE KDE 3.3.1)
Installed from:    Gentoo Packages
OS:                Linux

There are some wishes for an improvement of the keyboard navigation, but I think this is a new idea.

The keypad in the folder/mail view is just unused. It could provide an easy to use and very very fast one-hand-navigation. 

Key mappings:
4/6: close/open a node in a tree of grouped messages
8/2: one message up / one message down
9/3: half page up / half page down
7/1: one folder up / one folder down (open it, not only select it!)
5: one key reading. Similar to the space key, but focussing the next message when the slider is already down and the key is pressed a second time (prevents activation by mistake).

- Doing only have a page up/down (9/3), spares the "one line up/down keys", without scrolling too fast. Therefore it is better to keep the overview and scrolling is still fast enough.
- Using the arrow up/down key (8/2) feels just heaps better for navigating up and down (e.g. like in the file-list in konqueror)!
- Same for the left/right arrow key (4/6). 
- There was an argument against opening folders immediately: it could take some time to open it. Why not putting this into another thread or open it a bit delayed? Instant selection is better for a fast navigation.
- The arrows on the keypad make its use quite intuitive
- It is not necessary anymore to press the ctrl-key for folder navigation
- The +/- keys for jumping to an unread message are easy to reach
- The * and / keys could be used to jump to the previous/next unread message in a different folder
- There are still "0", "." and "enter" which could access other functions like "reply", "forward", "open", "flag" ...

I dare to say it is a complete solution for keyboard-navigation and I would really love to see this working :)