Inconsistent behaviour of QVBoxLayout

[spraff]

Hi there. I have a QWidget which contains a QScrollArea which contains a MyList which has a QVBoxLayout. MyList has a slot

void MyList :: add_new () {
	MyWidget * w = new MyWidget (this);
	layout () -> addWidget (w);
}

void MyList :: add_new () {
	MyWidget * w = new MyWidget (this);
	layout () -> addWidget (w);
}

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I can call add_new repeatedly from the MyList constructor and the behaviour is as expected: a new widget is added to the end of the list and eventually a scroll bar appears as the MyList widget grows.

If I call add_new later as the result of a user action, the height of the MyList widget is fixed and everything is squashed to accomadate the new MyWidget.

Is this a bug or do I need to change some setting?