grooter: of course you can try changing the layer boundary in case that's a problem, but there is a bug with the text tool
in 2.8 on windows that does exactly what you describe. i know it's been up for discussion here on gimp chat before (
http://gimpchat.com/viewtopic.php?f=4&t=6274&start=10) and it doesn't seem like it's going to get fixed. it has to do with windows coding, not really with gimp, it seems. my solution has been to select the text, then make a path from the selection and change the path til i get something that looks right.