Created attachment 527199 [details]
Screenshot

Environment:
Dev env, last commit's hash: 89fff67de9952ace82477571e54da17403952858

I don't have a reproducer for that, but when it occurs - all the available buttons in the line right below the main sub tabs do nothing.
Buttons for instance: the "New" button under the "Hosts" main tab, the "Edit" button when choosing specific data center from the grid under the "Data Centers" tab etc.

Note that it's not refreshing issue, neither session timeout one, since logout and login again or moving between tabs doesn't solves it, only JBoss restart solves it.

Note that I didn't check whether it happens in the buttons under the sub-tabs too.