Steps to reproduce / test case:

Open modal dialog (we'll call it A)
Open another modal dialog from this modal dialog (we'll call it B)
use QWidget::reject() to pop out of this modal dialog
the original modal dialog (A) does not become active again automatically. The same sometimes occurs when using QWidget::accept() to get out of B.

More information:

-If B is a sheet there is no problem.
-I believe this only effects Mac.
-I'm using Qt/Carbon.