how to draw on any window from a widget in python

I am new in python and i want to create a script in python which can let me draw or paint in my desktop or on any window like web browser etc.....

Can anybody tell me which library in python can i use to achieve something this.

As i want to draw directly on the desktop screen and not in any canvas or particular (seperate window for drawing)

From tkinter.colorchooser or something else.

The example image is shown below that's how i want.

how can i get a widget like this with only color option and default pen to draw.

Use python in-built library Tkinter.

from tkinter import *
from tkinter.colorchooser import askcolor


class Paint(object):

    DEFAULT_PEN_SIZE = 5.0
    DEFAULT_COLOR = 'black'

    def __init__(self):
        self.root = Tk()

        self.pen_button = Button(self.root, text='pen', command=self.use_pen)
        self.pen_button.grid(row=0, column=0)

        self.brush_button = Button(self.root, text='brush', command=self.use_brush)
        self.brush_button.grid(row=0, column=1)

        self.color_button = Button(self.root, text='color', command=self.choose_color)
        self.color_button.grid(row=0, column=2)

        self.eraser_button = Button(self.root, text='eraser', command=self.use_eraser)
        self.eraser_button.grid(row=0, column=3)

        self.choose_size_button = Scale(self.root, from_=1, to=10, orient=HORIZONTAL)
        self.choose_size_button.grid(row=0, column=4)

        self.c = Canvas(self.root, bg='white', width=600, height=600)
        self.c.grid(row=1, columnspan=5)

        self.setup()
        self.root.mainloop()

    def setup(self):
        self.old_x = None
        self.old_y = None
        self.line_width = self.choose_size_button.get()
        self.color = self.DEFAULT_COLOR
        self.eraser_on = False
        self.active_button = self.pen_button
        self.c.bind('<B1-Motion>', self.paint)
        self.c.bind('<ButtonRelease-1>', self.reset)

    def use_pen(self):
        self.activate_button(self.pen_button)

    def use_brush(self):
        self.activate_button(self.brush_button)

    def choose_color(self):
        self.eraser_on = False
        self.color = askcolor(color=self.color)[1]

    def use_eraser(self):
        self.activate_button(self.eraser_button, eraser_mode=True)

    def activate_button(self, some_button, eraser_mode=False):
        self.active_button.config(relief=RAISED)
        some_button.config(relief=SUNKEN)
        self.active_button = some_button
        self.eraser_on = eraser_mode

    def paint(self, event):
        self.line_width = self.choose_size_button.get()
        paint_color = 'white' if self.eraser_on else self.color
        if self.old_x and self.old_y:
            self.c.create_line(self.old_x, self.old_y, event.x, event.y,
                               width=self.line_width, fill=paint_color,
                               capstyle=ROUND, smooth=TRUE, splinesteps=36)
        self.old_x = event.x
        self.old_y = event.y

    def reset(self, event):
        self.old_x, self.old_y = None, None


if __name__ == '__main__':
    Paint()