During porting my app (VACALACa) to Qt 5 I've notices that QWidget in Qt 5 consumes mouseDoubleClickEvent i.e. parent widget doesn't receive it.
For comparison contextMenuEvent works fine (same as in Qt 4.8.0).
I've also found the change that is responsible for that and it looks like a bug.
In attachment proposed fix.
I'm just simple Qt user so pleas correct me if I'm wrong and this new behavior is "by design".

Steps to reproduce:
1) create widget with child widget inside.
2) overwrite mouseDoubleClickEvent in parent widget
Expected result:
mouseDoubleClickEvent in parent widget is called after double click on child widget.
Current result:
mouseDoubleClickEvent in parent widget is not called.

What is more method documentation is inconsistent with current implementation.