'Returns the line number from the y_pos.
:param y_pos: Y pos in the editor
:return: Line number (0 based), -1 if out of range'

def line_nbr_from_position(self, y_pos):

    editor = self._editor
    height = editor.fontMetrics().height()
    for (top, line, block) in editor.visible_blocks:
        if (top <= y_pos <= (top + height)):
            return line
    return (-1)
