This is a bug in JMenu on multi-monitor systems. I used Windows 2000, but I'd be willing to bet the bug is present on Solaris runnin Xinerama as well. The following assumes that your secondary display is positioned to the right of the primary.

To reproduce:
* start up Stylepad
* drag the Stylepad frame so that the "Debug" menu is right next to the edge of the screen
* bring down the Debug menu. The menu will span across the two screens.

With 1.3.1, the menu is displayed right-justified so it all appears on one screen.

Note 1: If you first resize and then drag Stylepad so that the Debug menu is forced to be heavyweight, the JMenu pops down right-justified, as desired.

Note 2: If you first drag, and then resize Stylepad when it is already at the edge of the screen (i.e. Stylepad is spanning two screens, with the Debug menu on the primary display, and then Stylepad is resized to be completely on the primary display), the JMenu will still popup left-justified, spanning the two screens.

Possibly related bugs are 4432432, 4425878, 4647105.