custom visual programming environments

I am trying to build a desktop application that uses python lib in backend and in front end i want to build a UI similar to Orange Canvas(visual programming) where there are widgets for each function and connect these widgets

I found this library called QT dataflow which states that it provides a generic template for custom UI but it is full of bugs and is not in active development

So doing changes in same library to get the job done ,I fixed one bug but connector events are pretty lame and not working is there any library i can use to do the same currently qt dataflow is in pyqt4...

also i want to build the same for web app .how can i approach this?