is there any Custom widget like the BluePrint or FlowGraph ?

is there any Custom widget like the BluePrint or FlowGraph as shown below?
if not, is there any good idea to realize it? a custom widget inherit from Listbox, and use the Cairo to draw the curves?
Thanks very much!
http://fc06.deviantart.net/fs71/f/20...rz-d7bmcno.png

http://staraban.com/wp-content/uploa...int-editor.jpg

You can implement it using Graphics View. Or Qt Quick, if you please.