Kubuntu 10.04, how do you get rid of the background image for the bar?

I want my desktop functional and not visually interesting.

The taskbar (sorry I forget the correct name) background makes it much harder to see the useful content, especially the icon for selecting between desktops, that uses the same shades as the default image.

I took a few google searches and a bunch of experiments just to get rid of the image (in favor of a solid color) for the main desktop. That dialog was not where I expected it and I wasted lots of time in dialogs for configuring the desktop appearance that don't offer that basic option. But I did find it. That still leaves an image as background for the bar, and I have no clue how to get rid of that image.

Try using gnome-panel or xfce4-panel instead of Plasma panel. But in this case you won't be able to put any of Plasma applets to the panel.

I guess I'll need to poke around a bit just to figure out how to try what you just said.

Do you really mean a Plasma panel can't avoid having an image as a background?

Also, you seem to be saying I can use a panel from a different desktop in KDE4. That is unexpected. I know I can run GUI programs from Gnome on a KDE desktop, but I thought a panel was more fundamentally related to the desktop package.

Also, I thought almost everything in KDE4 was a Plasma applet, so if a panel can't have Plasma applets, how can it do anything?

I'm just starting to learn KDE4 and don't know all that much about Kubuntu either.

I don't mean this, but having not found a way, i just offer a workaround.
A panel is just an application, much like file manager, terminal emulator etc.
Not everything. Plasma is just a workspace, i.e. desktop background with its applets as well as panel (which can be removed, another panel can be created, etc.), and panel can also use the same applets. Such KDE elements as file manager (Dolphin), terminal emulator (Konsole), system configurator, window manager (KWin) all aren't parts of Plasma thus don't need/provide any applets.

Panel from another desktop uses completely another toolkit, so it even may not know about Plasma applets.

In Kubuntu you will have to say
or something like that. XFCE panel is simpler than GNOME's one, but it requires much less libraries to be installed with it. GNOME panel supports XDG menu specification better than XFCE one.