Debugger should not allow put breakpoints if line number is missing or at least display a warning if it is not possible. According to Martin E. it works for Java but not for JavaFX. It is more important due to issues in current JavaFX SDK which doesn't generate line numbers in some cases due to complex compilation patterns.
Closing all bugs filed against JavaFX 1.x as wontfix. We will support JavaFX 2.0 - please keep opened only bugs against the new release. Thanks.