v0.4.6

Desktop app

• The lease follows the shell on screen. A window that opened a shell on another
  machine and then moved the screen on — to 本机, or to any other shell — used to
  leave that machine showing 正在被控制 with a keyboard that no longer worked.
  Switching away lets the lease go, the machine whose shell it is takes it back
  the way it does when a holder's lease lapses, and coming back to that shell
  drives it again without a click. The connection to that machine stays: it is
  the lease that moves, not the link.
• Picking a machine in the 机器 panel brings one of its shells on screen when this
  window has one open there, so 切到本机 means the screen as well as the panels:
  two panes and a pane that disagree about what is being worked on is one answer
  too many.
• The hub hands a lease nobody holds — released, let go by a detach, or simply
  lapsed — to the machine's own window when it is watching. A shell of a machine's
  is that machine's to type in, so a client that stops driving it cannot leave it
  mute with nothing on screen to say why.