I have a customDesignerWidget that inherits from QGroupBox. Inside the groupBox I have a QVBoxLayout.
By default when you do this, you can not interact with the QVBoxLayout, meaning that you can not drag any widgets to it in designer because the designer only sees the customDesignerWidget plugin.

Any ideas how I could give access to the QVBoxLayout so that when the user drags a widget over this custom designer widget, the widget would be added to the QVBoxLayout?