It sounds like you are attempting to do internationalization by adding
the Spanish equivalent inside the button instead of the standard Eclipse
way.
According to the following post from a few years back, it isn't
currently possible. In fact, the eclipse documentation states that you
aren't allowed to have line delimiters.
TF
http://dev.eclipse.org/newslists/news.eclipse.platform.swt/msg17475.html
Ben Smith wrote:
Hi all,
How can I set 2-line text in a Button? e.g., the first line is
"Cancel", the 2nd line will be "Cancelar".
Thanks,
Ben