Allow user to reopen the on-screen keyboard from the status bar

[mtlynch]

Blocked on #1512

One of the issues that catches some users by surprise is that if they hide the on-screen keyboard, they can't bring it back from the same place.

• Example: HomeNetworkGuy's review mentions this as a stumbling block @ 11:00

We should add a more obvious / more intuitive way for the user to bring back the on-screen keyboard after they hide it.

[gazhay]

Unless I'm missing something - the onscreen keyboard quite often obscures the screen - meaning you have to minimise it (and then this issue happens)

The keyboard auto hiding and displaying like a taskbar would be ideal.