Is there a way to add "magins" to the active screen area?

I'm using lemonbar as my panel, so I removed the JWM tray. Lemonbar doesn't move windows out of the way, so it will overlap.
Is there any way to add a n pixel border to the top of the screen, that window's cannot occupy?

Currently I am just using an empty tray:

<Tray x="0" y="0" delay="1000" height="26" autohide="off">
    <Spacer></Spacer>
</Tray>

Which works fine, just wondering if there is a more intended solution that I missed.

[yetanothergeek]

I don't know if it will make much difference but you might look at the <Swallow> tag.