code: def update(event):
      if event.xdata is None:
          label.set_markup("Drag mouse over axes for position")
      else:
          label.set_markup(
              f'<span color="#ef0000">x,y=({event.xdata}, {event.ydata})</span>'
          )
  
imports: import matplotlib
  import gi
  import matplotlib.pyplot
  from gi.repository import Gtk
label_desc: Use image node_id 1 for calling a global function with example usage: update(event) without return types