To add the capability to draw irregular lines, we just need to define the method named draw_irregular_line. To specify options that appear in the top bar, we need to define the method named draw_irregular_line_options.

We define the draw_irregular_line method as follows (see code 6.07.py):

def draw_irregular_line(self):
 self.current_item = self.canvas.create_line(
   self.start_x, self.start_y, self.end_x, self.end_y, fill=self.fill, 
     width=self.width)
 self.canvas.bind("<B1-Motion>", self.draw_irregular_line_update_x_y)

def draw_irregular_line_update_x_y(self, event=None):
 self.start_x, self.start_y = self.end_x, self.end_y
 self.end_x, self.end_y = event.x, event.y
 self.draw_irregular_line()

The preceding code is similar to the code for draw_line, except that it adds an extra line that binds mouse-clicked movements to a new method that replaces the start x, y coordinates with the end x, y coordinates and again calls back the draw_irregular_line method, thereby drawing in a continuous manner.

The options that show in the top bar are defined using the following method (see code 6.07.py):

def draw_irregular_line_options(self):
  self.create_fill_options_combobox()
  self.create_width_options_combobox() 

Now we can draw irregular lines on the canvas. However, since we have modified the mouse binding, all other methods will also start to draw in a continuous manner. 

We, therefore, need to rebind the buttons back to their original bindings. We do that by modifying on_tool_bar_button_clicked to call bind_mouse, which then restores the mouse binding to its original behavior.

This will bind the same event to method1 and method2.