import tkinter as tk

def clickedOnTest(event, test):
    start = test.index(('@%s,%s wordstart' % (event.x, event.y)))
    end = test.index(('@%s,%s wordend' % (event.x, event.y)))
    word = test.get(start, end)
    print("%s - %s" % (start, word))

root = tk.Tk()

# No tags, expected behavior
test = tk.Text(root)
test.bind("<Button-1>", lambda e: clickedOnTest(e, test))
test.grid()
test.insert(1.0, "[testing]\n**testing]")

# Words tagged, unexpected behavior 
test2 = tk.Text(root)
test2.grid()
test2.bind("<Button-1>", lambda e: clickedOnTest(e, test2))
test2.insert(1.0, "[testing]\n*testing]")
test2.tag_add("testing1", 1.1, 1.8)
test2.tag_add("testing2", 2.1, 2.8)

# not at edge and tagged, expected behavior
test3 = tk.Text(root)
test3.grid()
test3.bind("<Button-1>", lambda e: clickedOnTest(e, test3))
test3.insert(1.0, "word [testing]\n[[testing]")
test3.tag_add("testing3", 1.6, 1.13)
test3.tag_add("testing4", 2.2, "2.9")

root.mainloop()