Comment 237 for bug 25830

Basic designs are not solid, yet.

The problem is that users can close the original window (or tab) before
choosing some option in external-app dialog. This could causes multiple
bad results. It's okay to open it in a new tab, please think about such
a link:

<a href="unknown_mime.txt" target="my_target"> See the target. </a>

In this case, user may close "my_target" window before loading any
content into it. Gecko should force to open a new window nonetheless,
on user chosing "Handle inside Gecko"?

In summary, I think external-app window should be a modal dialog. Or
it needs a way to protect original DOM window, such as overlapping
bar or something like that.