How to gray out a menu item in Qt

Question

I'm building a small program in Qt with menu bars (menuBar) using C++ and I would like to know how to gray out (eg. disable) an item of the menu when a certain variable is activated. Is it possible?

Answer 1

If you know an index of the corresponding QAction :

QMenu::actions.at(i).setEnabled(false);

P.S. As kindly prompted below, setEnabled(bool) and setDisabled(bool) are slots (so is toggle()), so they can be connected to a signal indicating a need to change the availability of the action.