If a ticket is hidden, it is still counts into the dashboard counter. There's no way to view hidden tickets and to unhide an already hidden ticket, when you navigated away from its page.
So:
hidden tickets should be excluded from the dasboard counters
there should be a tab for hidden tickets (for admins)
optional: there should be a confirmation dialog before hiding a ticket
If a ticket is hidden, it is still counts into the dashboard counter. There's no way to view hidden tickets and to unhide an already hidden ticket, when you navigated away from its page.
So: