Deny leases can’t easily be set to start in the future

We’ve hit a usability problem with leases: because by default their expiration date is set to two days in the future, they cannot be easily set to start after that date. Which kind of makes sense, until you realise that clearing End date by hitting Close still won’t allow that (sic!). So to set an infinite lease that starts in 3 days, you first have to

1. manually set the End date/To field to be after that
2. set the Start date/From field to what you want
3. and only then you can clear the dud End date/To field you had to set in pt. 1

At the very least, clearing End date/To should free Start date/From calendar/field to allow for any date in the future.

Additionally, a small further problem: dates on committed leases should reveal exact date/hours on hover. Otherwise, in the real example above, it was not possible to set a Deny lease to start **exactly** when active Allow lease ends without resorting to API information.

Only because Leases, related to: https://github.com/guardian/grid/issues/3860