Regression: launcher unhides+rehides all the sodding time

Please excuse the near expletive. Regression introduced with unity=3.4.2-0ubuntu1 (this Thursday evening).

The launcher now pops out (unhides) and disappears (rehides) semi-continuously on all sorts of perfectly normal actions:

  1. Right-click on this very text entry box (unhide+hide)
  2. Un-right-click on this text box (unhide+hide again)
  3. Press Alt-tab (unhide+hide)
  4. Drift mouse over global menu (unhide+hide)
  5. Maximise/Demaximise window (even when both states cover full screen size)
  6. ad infinitum...

This is indescribably annoying. It's a cross between a hyperactive version of the crazy frog and the worst Macromedia Flash advert you've ever seen, anthropomorphised and having gained a serious methamphetamine addiction.

Reproducible: (Not necessarily minimal testcase)

 1. Have a maximised gnome-terminal;
 2. Select some text in the terminal with the mouse
 3. trigger scale with Super+w

"unity --replace" should get you out of it again.