Version:            (using KDE KDE 3.1.2)
Installed from:    Gentoo Packages
Compiler:          gcc 3.2.3 CFLAGS="-O3 -march=athlon-xp -funroll-loops -fprefetch-loop-arrays -pipe -fomit-frame-pointer -ffast-math -finline-functions -m3dnow -mmmx -msse"
OS:          Linux

I like  the kasbar better than the taskbar, so I tried to set both side-by side at the bottom of the screen. If I set both at the middle, kicker stays in the bottom of the screen, and kasbar on top of kicker. I expected this. But this is what I did not expect: when I set kicker horizontally to the bottom right side of the screen, taking up less than 100% of the screen, without autostrtech, and kasbar horizontally OR vertically to the bottom left, there is a useless rectangle at the bottom left which will never be used by kicker, but kasbar is not allowed to use it too. IF I put both of them horizontally, one to the bottom left, and the other to the bottom right, I would like to see them take up only as much space as they need, and coexist side by side. Creative ascii-art:
***** -> free space 
===== -> panel
""""" -> kasbar

Currently, it is like this:

***************
"""""**********
**********=====

which makes no sense, look at the free space!
It should be like this:
***************
***************
"""""*****=====
Kasbar also does not show buttons to scroll when there is not enough space to show all images (just found it!) , I will fill another bug for this. 

Proposed solution:

I think there should be priorities for taking up screen space space. 
In the control center, we have the Desktop -> Panels -> Arrangement
There we could/should have a Priority/Importance setting, which means "who takes up screen space first"
it could be as simple as using the left list in this screen and add up/down buttons to switch the order of the "panel applications" (and allow them to be draggable up/down). The one in the top claims it space first, but only what it needs, not the full screen width. The others go one after the other. This is the 1.0 setting to be implemented.
Others will certainly want one panel to "squish" the other panel if it suddenly grows (as the kasbar does), but this could be left for version 2.0, as it is more complicated to agree in a "best way" to do. 
Anyway, this is my suggestion for version 2.0:
Let panels be simply "Greedy" or "Shy". Greedy panels try to squish the other panels before they show up scroll buttons for lack of space. Shy panels never try to take the other panels' space. when two greedy panels collide, a) It does not claim the others space (my preferred) or b) the priority solves who wins and squish the other. Shy panels need to have a minimum width/height, though, because they must have a meaningful area in which to scroll content.