I am creating a graphical interface with glade that contents a treeview. 
I want to have a button that is initially enabled by doing a simple click on a row of the treeview. 
I am using row-activated, but when I activate a row for the first time I have to double click the row.
Which signal should I use to detect the click to activate the row with a single click?
I know this is an old question, but for future reference, for Python3 and Gtk3 what worked for me was:

    myTree.set_property('activate-on-single-click', True)
Tree view row activated with ONE click