Python

#!/usr/bint/python

import tkinter as tk

class myGUI(object):

    def __init__(self):
        self.main_window = tk.Tk() # create root window
        self.main_window.pack_propagate(0)
        self.main_window.geometry("500x500")
        self.main_window.configure(bg = "#AAA5A4")

        self.frame1 = tk.Frame(self.main_window, bg = "blue", bd = 5, relief = "groove") # create frame 1
        self.frame2 = tk.Frame(self.main_window, bg = "yellow", bd = 5, relief = "groove") # create frame 2

        # add components into frame1
        self.label1 = tk.Label(self.frame1, text = "US Liquid Gallon:", bd = 5, relief = "ridge")
        v = tk.StringVar(self.frame1, value='10')
        self.entry = tk.Entry(self.frame1, textvariable = v, bd = 5, relief = "sunken", justify = "center")

        self.label1.place(relx = 0, rely = 0.1, relheight = 0.8, relwidth = 0.5, anchor = "nw")
        self.entry.place(relx = 0.5, rely = 0.1, relheight = 0.8, relwidth = 0.5, anchor = "nw")
        self.frame1.place(relx = 0, rely = 0.02, anchor="nw", relheight = 0.3, relwidth = 1)

        # add components into frame2
        self.label2 = tk.Label(self.frame2, text = "Liters:", bd = 5, relief = "ridge")
        self.label3 = tk.Label(self.frame2, text = "37.8541", bd = 5, relief = "sunken")

        self.label2.place(relx = 0, rely = 0.1, relheight = 0.8, relwidth = 0.5, anchor = "nw")
        self.label3.place(relx = 0.5, rely = 0.1, relheight = 0.8, relwidth = 0.5, anchor = "nw")

        self.frame2.place(relx = 0, rely = 0.34, anchor = "nw", relheight = 0.3, relwidth = 1)

        # add components into frame3
        self.frame3 = tk.Frame(self.main_window, bg = "red", bd = 5, relief = "groove")
        self.button = tk.Button(self.frame3, text = "Convert", bd = 20, relief = "raised", bg = "green", command =self.convert)

        self.button.bind("<Button-1>", self.mouseclick)
        self.button.bind("<ButtonRelease-1>", self.mouserelease)
        self.button.pack(side = "left", expand = True, fill = "both")

        self.frame3.place(relx = 0, rely = 0.66, anchor = "nw", relheight = 0.3, relwidth = 1)

        tk.mainloop()

    def convert(self):
        value = self.entry.get()
        self.label3.config(text = str(float(value)*3.78541))

    def mouseclick(self, event):
        self.frame3.config(bg = "#395497", relief = "sunken")
        self.button.config(activebackground="blue") # button color is supported in Mac

    def mouserelease(self, event):
        self.frame3.config(bg = "red", relief = "groove")

def main():
    gui = myGUI()

if __name__ == '__main__':
    main()

pack(), organizes widgets in blocks in parent widget

expand, allow widget to fill any space in the parent widget
fill, expand direction, "x", "y", "none", "both"
side, figure out the location in parent widget, "top", "left", "right", "bottom"

grid(), organizes widgets in a table-like structure in parent widget

row, the row to put widget in
column, the column to put widget in

place(), organizes widgets by placing them in a specific position in the parent widget

anchor, The exact spot in parent widget, "nw", "n", "e", "s", "w", "ne", "se", "sw"
height, width, height and width in pixels
relheight, relwidth, height and width as a fraction of the height and width of the parent widget
x, y, horizontal and vertical offset in pixels
relx, rely, horizontal and vertical offset as a fraction of the height and width of the parent widget

<Button-1>, events that mouse button has been pressed while the mouse cursor is positioned over the widge, Button 1 is the left mouse button, Button 3 is the right, and Button 2 the middle button

<ButtonRelease-1>, indicates that the left button has been released

<Enter>, <Leave>, the mouse curson has entered or left the widget

<Key>, key on the keyboard was pressed

<Return>, the enter key is pressed

<Configure>, the widget has changed size.

import Tkinter as tk

class myGUI(object):

    def __init__(self):
        self.window = tk.Tk()
        self.window.geometry("200x100")
        self.window.resizable(0, 0)

        self.frame = tk.LabelFrame(self.window, text = "Scrolling", bd = 2, relief = "sunken")
        self.frame.place(x = 10, y = 10, height = 80, width = 180, anchor = "nw")

        self.scrollbar = tk.Scrollbar(self.frame)
        self.scrollbar.place(x = 160, y = 0, height = 80, width = 10, anchor = "nw")

        self.listbox = tk.Listbox(self.frame, bg = "blue", bd= 0, yscrollcommand=self.scrollbar.set)
        self.listbox.place(x = 0, y = 0, height = 80, width = 160, anchor = "nw")
        self.scrollbar.config(command=self.listbox.yview)

        for i in range(100):
            self.listbox.insert(i, i)

        tk.mainloop()

def main():
    gui = myGUI()

if __name__ == '__main__':
    main()