Ok, I am very sad that this plasmoid has not been made...
quicklaunch looked promising, but it doesn't offer multiple columns, but it might be a good start.
Maybe there are errors or extra complications when nesting panels? because I want to make two panels, in one panel. either horizontally or vertically. and then be able to continue to nest. so a 4x4 would be 3 panels. Shouldn't take much resources... and this would allow for custom shaped items too.
I have a taskbar setting like this: (kde3 and windows)
F C C
Prog1 Firef Chrom VMware KDE Dolphin
x y z 12:24pm 7/15/2010
and in KDE4, it is
1 0 0000 1 1 0 0 1 1 0 0 1 1 0 0000 1
CCCCC CC C C C C CCCC
(you get the idea, hopefully, the Icon from Chromium is larger than all of the program starters in windows.. (or if I had the panel horizontal they would also be small)
a 4x4 grid, where application launchers are specified explicity, with no drags or drops.
accept drags and drops of application icons, add rows and columns automatically. (basically emulate the kde3 widget)