please see bugzilla 195788
XPI installs fail on Mac OS X builds of 1.3b.
Install says it is happening, but it never restarts the browser and
previous components get removed as well as the splash screen.
chatzilla and venkman xpi's are what I've been trying.
Same XPI's install fine on NS 7.0 and Moz 1.0.1 on OS X
