We have a QTreeView that is linked to a data model, but there is no datachanged() signal being expressly sent to a subclassed QTreeView. Nonetheless, it updates the view under certain circumstances. With Linux and Windows, it updates when the mouse moves across the widget. With Mac OSX it updates when the focus is changed.

There is no logic in our subclass which follows the mouse movement or the window focus. Is this a bug in our software, a Qt bug, or a Qt feature which we simply aren't understanding?

Here's a video of the behavior on Windows/Linux:

http://youtu.be/1rVhB60VqBQ

P.S. Using Qt 4.8.4.