A trivial thing, surprised nobody asked for it before.

When more hosts / host groups are selected, the navigation header disappears, forcing me to remove all hosts but one so header appears, make switch and then re-add all hosts.

It would be more comfortable if header stayed so I can switch with any number of hosts in filter.

I often find myself needing to switch between Items and their Discovery rules on multiple hosts. Most common reason is changes to LLD filters or changes on remote systems, which require me to switch between discovery to re-run LLD and items to see if it worked right. If not, I perform more changes to LLD filters or remote systems and repeat.

This change seems very easy.