Canvas tag bug? v1.0

import tkinter as tk
from tkinter import ttk
from tkinter import messagebox
from functools import partial


'''
Ctag Tester v1.0
29 February 2020
Written for Python 3.7.0 (v3.7.0:1bf9cc5093, Jun 27 2018, 04:06:47) [MSC v.1914 32 bit (Intel)] on win32 / Windows 10 / VS Code (ide)

This is a demo of a tkinter / canvas bug. Or something. (?)

1. Each of the two squares on the canvas should report its tag for a mouse-1-down and mouse-1-up event.

2. It always reports properly if you click and release on the same item.

3. PROBLEM: If you click down on one square and then drag to the other square, the mouse-up event gives the same tag as the mouse-down event, even though they did not occur on the same item.

4. The mouse x-y coordinates are also reported, and those always report correctly wherever those two events occur.

5. What I assumed should happen is that the mouse-down event should get the tag of the item that it occurs on, and the mouse-up event should get the tag of the item that it occurs on.

6. ???

7. Profit!
'''


def main():
    program = TestProgram1()
    program.window.mainloop()

class TestProgram1:

    def __init__(self):
        self.window = tk.Tk()
        self.window.title( "Ctag Tester v1.0" )
        self.window_width = 800
        self.window_height = 600
        self.window.minsize(self.window_width, self.window_height)
        self.window_position_x = 40
        self.window_position_y = 40
        self.window.geometry('%dx%d+%d+%d' % (self.window_width, self.window_height, self.window_position_x, self.window_position_y))
        self.window.resizable(False, False)



        x_pos = 20
        y_pos = 20
        self.staticlabel_38 = tk.Label(master=self.window, text="mousedown xy:")
        self.staticlabel_38.place(x=x_pos, y=y_pos)
        x_pos = 180
        y_pos = 20
        self.staticlabel_42 = tk.Label(master=self.window, text="mouseup xy:")
        self.staticlabel_42.place(x=x_pos, y=y_pos)

        x_pos = 20
        y_pos = 50
        self.label_mousedown = tk.Label(master=self.window, text="[none]")
        self.label_mousedown.place(x=x_pos, y=y_pos)
        x_pos = 180
        y_pos = 50
        self.label_mouseup = tk.Label(master=self.window, text="[none]")
        self.label_mouseup.place(x=x_pos, y=y_pos)

        x_pos = 20
        y_pos = 100
        self.staticlabel_55 = tk.Label(master=self.window, text="mousedown tag:")
        self.staticlabel_55.place(x=x_pos, y=y_pos)
        x_pos = 180
        y_pos = 100
        self.staticlabel_59 = tk.Label(master=self.window, text="mouseup tag:")
        self.staticlabel_59.place(x=x_pos, y=y_pos)

        x_pos = 20
        y_pos = 130
        self.label_tagdown = tk.Label(master=self.window, text="[none]")
        self.label_tagdown.place(x=x_pos, y=y_pos)
        x_pos = 180
        y_pos = 130
        self.label_tagup = tk.Label(master=self.window, text="[none]")
        self.label_tagup.place(x=x_pos, y=y_pos)

        x_pos = 350
        y_pos = 40
        self.canvas1 = tk.Canvas(master=self.window, width=400, height=400)
        self.canvas1.place(x=x_pos, y=y_pos)
        self.canvas1.create_rectangle(2, 2, 400, 400, outline='black', fill='white')

        target_1 = self.canvas1.create_rectangle(80, 80, 180, 180, outline='black', fill='green', tags=('greenbox'))
        self.canvas1.tag_bind('greenbox', '<Button-1>', partial(self.chart_item_mousedown_event, target_1))
        self.canvas1.tag_bind('greenbox', '<ButtonRelease-1>', partial(self.chart_item_mouseup_event, target_1))

        target_2 = self.canvas1.create_rectangle(240, 180, 340, 280, outline='black', fill='red', tags=('redbox'))
        self.canvas1.tag_bind('redbox', '<Button-1>', partial(self.chart_item_mousedown_event, target_2))
        self.canvas1.tag_bind('redbox', '<ButtonRelease-1>', partial(self.chart_item_mouseup_event, target_2))



    def chart_item_mousedown_event(self, c_handle, event):
        temp_tag = self.canvas1.gettags(c_handle)
        if temp_tag == "":
            self.label_tagdown.config(text='[none]')
        else:
            self.label_tagdown.config(text=temp_tag)
        m_event = "x:" + str(event.x) + ", y:" + str(event.y)
        self.label_mousedown.config(text=m_event)



    def chart_item_mouseup_event(self, c_handle, event):
        temp_tag = self.canvas1.gettags(c_handle)
        if temp_tag == "":
            self.label_tagup.config(text='[none]')
        else:
            self.label_tagup.config(text=temp_tag)
        m_event = "x:" + str(event.x) + ", y:" + str(event.y)
        self.label_mouseup.config(text=m_event)



if __name__ == "__main__":
    main()