Mastering GUI Programming with Python

The check _delete _btn () method

Our last callback is the simplest of all, and it looks like this:

    def check_delete_btn(self):        self.del_button.setDisabled(            self.event_list.currentRow() == -1)

This method simply checks whether there is no event currently selected in the event list widget, and it enables or disables the delete button accordingly.

Back in __init__(), let's connect to this callback:

        self.event_list.itemSelectionChanged.connect(            self.check_delete_btn)        self.check_delete_btn()

We're connecting this callback to the itemSelectionChanged signal. Note that we've already connected that signal to another slot as well. Signals can be connected to any number of slots without a problem. We also call the method directly, so that the del_button ...