[JWait]

One of the problem is that the first "box" in your right column is using "DialogTitle", "DialogBorder" and "DialogBox" classes instead the normal "VertMenuTitle", "VertMenuBorder" . and "VertMenuBox". This is probably because dialog.tpl is being called from the template for that "box" instead of menu.tpl. This is evidenced by the rounded upper left hand corner and green outline instead of black, the same as your "dialog" boxes (like "featured products" has on your main page).

From the thread you referenced about "Adding HTML Boxes on Main Page", it calls the template "mycustombox.tpl", so it would be that or whatever you named it (onsale.tpl?) that controls that box. It needs to have menu.tpl instead of dialog.tpl control that space.