code: def gui_getFile():
      
      import tkinter as tk
      from tkinter import filedialog
      root = tk.Tk() # this is natively supported by python
      root.withdraw() # hide main window
      root.wm_attributes('-topmost', 1) # always on top
      fname = filedialog.askopenfilename(title = "select ABF file",
                                         filetypes=[('ABF Files', '.abf')],
                                         initialdir=os.path.dirname(abfFname_Load()))
      if fname.endswith(".abf"):
          abfFname_Save(fname)
          return fname
      else:
          print("didn't select an ABF!")
          return None
docs: Launch an ABF file selection file dialog.
      This is smart, and remembers (through reboots) where you last were.