drag window

import tkinter as tk
import tkinter.ttk as ttk


class App(tk.Tk):
    def __init__(self):
        super().__init__()
        self.rowconfigure(0, weight=1)
        self.columnconfigure(1, weight=1)
        self.title('Default Demo')
        self.geometry('800x800')


def main():
    app = App()

    dw = tk.Toplevel()
    dw.overrideredirect(True)
    dw.wait_visibility(app)
    dw.wm_attributes('-alpha', 0.2)
    dw.wm_attributes("-topmost", True)
    dw.config(bg='#00aaff')
    dw.withdraw()

    def drag(event):
        x, y = app.winfo_pointerxy()
        width = event.x-app.anchor_x
        height = event.y-app.anchor_y

        if width < 0:
            coord_x = event.x+app.winfo_rootx()
            width = app.anchor_x - event.x
        else:
            coord_x = app.anchor_x+app.winfo_rootx()

        if coord_x+width > app.winfo_rootx()+app.winfo_width():
            width -= (coord_x+width)-(app.winfo_rootx()+app.winfo_width())
        elif x < app.winfo_rootx():
            width -= (app.winfo_rootx() - x)
            coord_x = app.winfo_rootx()

        if height < 0:
            coord_y = event.y+app.winfo_rooty()
            height = app.anchor_y - event.y
        else:
            coord_y = app.anchor_y+app.winfo_rooty()

        if coord_y+height > app.winfo_rooty()+app.winfo_height():
            height -= (coord_y+height)-(app.winfo_rooty()+app.winfo_height())
        elif y < app.winfo_rooty():
            height -= (app.winfo_rooty() - y)
            coord_y = app.winfo_rooty()

        dw.geometry(f'{width}x{height}+{coord_x}+{coord_y}')

    def button_press(event):
        dw.deiconify()
        app.anchor_x, app.anchor_y = event.x, event.y
        app.bind('<Motion>', drag)

    def button_release(event):
        dw.withdraw()
        dw.geometry('0x0+0+0')
        app.unbind('<Motion>')

    app.bind('<Button-1>', button_press)
    app.bind('<ButtonRelease-1>', button_release)

    app.mainloop()


if __name__ == '__main__':
    main()