The "Mantis" block of options in the job configuration page is shown between some options of the top basic options block (between "Discard Old Builds" and "This build is parameterized" in my install). This breaks the flow of the basic options and is confusing because it looks like options like "Disable Build" are part of Mantis configuration.
The block of options should be moved below in the page, where it does not break any existing block of options (maybe between "Source Code Management" and "Build Triggers").