I am using a QTreeView with a model that populates items with children on demand, i.e., only when the item is expanded. To achieve this, the model returns true for hasChildren() before the first expansion, while rowCount() returns 0.
This worked well, until I tried to add a proxy between the model and the view, so that items could be filtered. The proxy returns false for hasChildren(), regardless of the result provided by the underlying model. This means that the expansion icons are not drawn, and the use can not open new items.

Is there another way to force the tree to draw the expansion icons?

Thanks,
--Elad