I found out that something is wrong with the <rect/> object. The edges parameter does not work correctly. First, according to this site
, the edges should be separated by a pipe (|) but that doesn't work. Instead, the semicolon (;) does work. Weird.
But, that's not all. If you use edges="left;right", the entire left side is shown, but only the right side without the top pixel and bottom pixel. I guess they belong to "top" and "bottom", but it would be better if the corner pixels belonged to both left/right and top/bottom.