Well making my own widget is an option, and can't use right mouse click because my requirement is to make a hierarchical tree structure with each entry of tree containing a check-button. Hence whenever each check-button is selected all its child node should get selected, but when de-select a check-button, the parent check-button will get partially de-selected(third state) or or totally de-selected(only if all its child node are de-selected))

What i was thinking that each check-button has a variable associated to it, and when i change the value of that variable to on/off state, the check-button gets selected/de-selected automatically. So if i know how does tk is exactly implementing this behavior, i can make changes in that area of code to add my functionality. Is it possible?