It's worse than that. When the primary screen is not at the top-left corner of the virtual desktop, popup menus (including the awesomebar) may appear partially or completely off-screen.
Here's an ASCII-art diagram:
+----+
| 2 |
+----| |
| 1 | |
+----+----+
1 is the internal screen, 2 is the external screen. Firefox appears to use the dimensions of screen (1) to limit the area of its popups, but it assumes that that area starts at the top-left corner.
It's worse than that. When the primary screen is not at the top-left corner of the virtual desktop, popup menus (including the awesomebar) may appear partially or completely off-screen.
Here's an ASCII-art diagram:
+----+
| 2 |
+----| |
| 1 | |
+----+----+
1 is the internal screen, 2 is the external screen. Firefox appears to use the dimensions of screen (1) to limit the area of its popups, but it assumes that that area starts at the top-left corner.
Platform: Linux, using RandR 1.3.