def check_mouse_ax(event, self):
    """Grabs the mouse axes position

    Parameters
    ==========
    event (matplotlib event)
        the matpotlib event
    self (SXDMFrameset)
        the sxdmframeset

    Returns
    =======
    Nothing - just checks which axis the mouse is in
    """
    if event.inaxes == self.fluor_ax:
        self.viewer_currentax = self.fluor_ax
    elif event.inaxes == self.roi_ax:
        self.viewer_currentax = self.roi_ax
