Comment 6 for bug 1268167

I can confirm the same behaviour. The "super" key method works fine. My launcher is set to reveal when the mouse goes to the top left corner but it does not behave that way on the external monitor configured to the right of the laptop monitor.

The behaviour appears to be top left of the entire display area rather than "per monitor": switching the external monitor to be left of the laptop monitor allows the launcher to reveal as expected on the external monitor but not on the laptop monitor.

WM_CLASS for the launcher is "not found" as shown by "xprop WM_CLASS" and clicking on the launcher bar; presuming "unity" package.

System:
Lenovo Z580 Intel(R) Core(TM) i5-3210M CPU @ 2.50GHz

Ubuntu:
12.04.4 LTS

Kernel:
Linux 3.8.0-35-generic #50~precise1-Ubuntu SMP Wed Dec 4 17:25:51 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux

Graphics:
00:02.0 VGA compatible controller [0300]: Intel Corporation 3rd Gen Core processor Graphics Controller [8086:0166] (rev 09)