Recently I changed my computer and upgraded to Slackware 12.
I'm using blackbox-0.65.0-i486-4, default in Slackware.
When I have the toolbar at bottomcenter, it is around 3 mm above the bottom of the screen. When I put it at topcenter it is close to the top of the screen as it should be.
I think it might be a graphic card stuff because someone else told me he was using slackware 12 with blackbox with the toolbar at the same place without having this issue.
My graphic card is a nvidia 6200 onboard.