How to remove the horrible hover menu popups in Jenkins.

jenkins.txt

Install "Simple Theme Plugin" - this gives you some theme settings

Configure System > URL of theme CSS = /userContent/noBreadcrumbPopups.css

This maps to something like /var/lib/jenkins/home/userContent/noBreadcrumbPopups.css

Create this file with contents:

#breadcrumb-menu, #breadcrumb-menu * {
  display: none !important;
}