ddrops.py

from tkinter import *
from tkinter import ttk

root = Tk()
root.title('Codemy.com - Dependent Dropdowns')
root.iconbitmap('c:/gui/codemy.ico')
root.geometry("500x400")

# Creating a list of sizes
sizes = [
	"Small",
	"Medium",
	"Large"
]

# Create a list of colors
small_colors = [
	"Red",
	"Green",
	"Blue",
	"Black"
]

medium_colors = [
	"Red",
	"Green"
]

large_colors = [
	"Blue",
	"Black"
]

def pick_color(e):
	if my_combo.get() == "Small":
		color_combo.config(value=small_colors)
		color_combo.current(0)
	if my_combo.get() == "Medium":
		color_combo.config(value=medium_colors)
		color_combo.current(0)
	if my_combo.get() == "Large":
		color_combo.config(value=large_colors)
		color_combo.current(0)

# Create a drop box
my_combo = ttk.Combobox(root, value=sizes)
my_combo.current(0)
my_combo.pack(pady=20)
# bind the combobox
my_combo.bind("<<ComboboxSelected>>", pick_color)

# Color Combo box
color_combo = ttk.Combobox(root, value=[" "])
color_combo.current(0)
color_combo.pack(pady=20)

# Frame
my_frame = Frame(root)
my_frame.pack(pady=50)

# List boxes
my_list1 = Listbox(my_frame)
my_list2 = Listbox(my_frame)
my_list1.grid(row=0, column=0)
my_list2.grid(row=0, column=1, padx=20)

def list_color(e):
	my_list2.delete(0, END)
	if my_list1.get(ANCHOR) == "Small":
		for item in small_colors:
			my_list2.insert(END, item)
	if my_list1.get(ANCHOR) == "Medium":
		for item in medium_colors:
			my_list2.insert(END, item)
	if my_list1.get(ANCHOR) == "Large":
		for item in large_colors:
			my_list2.insert(END, item)

# add items to list1
for item in sizes:
	my_list1.insert(END, item)

# Bind The Listbox
my_list1.bind("<<ListboxSelect>>", list_color)

root.mainloop()