We couldn't get this working for 3.1 beta 1, but it should be doable.
The migration assistant disappears behind the 3pane on first launch, because the system integration dialog pops up, pulling the 3pane to the front. And on OS X, there's no indication that the migration assistant is even there. (This would also fix bug 560745, because you couldn't close the 3pane if this modal window was on top of it.) Later, Blake.
Ick, this hurts the migration assistant functionality a bunch, and needs to block, I think.
That migration dialog would need to appear before any password requests are presented to the user (in fact, before any login takes place). See dependent bug 522631 and bug 563290.
Created attachment 443605 [details] [diff] [review] A patch to make the migration assistant modal on first launch. Hey Bryan, I think this is probably a reasonable place to ask for a UI-review. I'm setting an attribute on the buttons to indicate whether we're on the first run (and therefore modal) or not, and then switching on that in the CSS. (We might want to rename the attribute to "isUpgrade", or something, as well. Your call.) One thing that's different is that we can't resize the modal dialog anymore, but I'm not sure how important you feel that is. As always, lemme know if you want a try-server build to play with. (Oh, and I've only tested it on Mac.) Thanks, Blake.
Comment on attachment 443605 [details] [diff] [review] A patch to make the migration assistant modal on first launch. I've only tested this on the Mac so far but it feels good.
Did anyone verify what happens if a password dialog (e.g. master or normal) is displayed when starting up? Especially on Mac as that can cause hangs...
I just tested that, and the password dialog doesn't get displayed until after the migration assistant closes. (The order of dialogs I see in my tests on Mac is: Migration Assistant » Default Client » Mail server password.) Later, Blake.
Checked in as: http://hg.mozilla.org/comm-central/rev/c7d38819e838 and http://hg.mozilla.org/releases/comm-1.9.2/rev/c6f8c6e66fb8