Zoom in/out/reset

def zoom(self, factor):
        """Zoom in/out/reset"""
        editor = self.get_current_editorstack().get_current_editor()
        if factor == 0:
            font = self.get_plugin_font()
            editor.set_font(font)
        else:
            font = editor.font()
            size = font.pointSize() + factor
            if size > 0:
                font.setPointSize(size)
                editor.set_font(font)
        editor.update_tab_stop_width_spaces()