How/Can to create a function to left click a node?

[ipa-rwu]

This Tool is really useful! I want to extend this tool. But I am new to QT.

I am wondering if it is possible to create a menu when I left click one of the nodes in the graph.

I saw that when I move the mode to the node, it shows me the node name. And when I move to the connection line, it shows me topic information. How does it work?

I really appreciate any help and any hint.