Add custom QTreeView in VS .NET

[wysota]

Or create a widget plugin out of your widget, but that's more compilcated than jpn's solution.

[wind]

Thanks. "Promote to Custom Widget" is the right way.

[wysota]

They are both "the right ways". Promoting a widget is just a simpler one (but also doesn't allow you to manipulate distinct features of your custom widget from within Designer).