Python TKinter binding to enter key

I've made some changes to your code, labeling the comments T3 for visibility. This allows you to use Return on the Buttons and Text field, with the "connect" button "rescuing" focus, in effect.

from Tkinter import *class MyApp:    def __init__(self, parent):        #------ constants for controlling layout of buttons ------        button_width = 15        button_padx = "2m"        button_pady = "1m"        buttons_frame_padx =  "3m"        buttons_frame_pady =  "0m"        buttons_frame_ipadx = "3m"        buttons_frame_ipady = "0m"        # -------------- end button constants ----------------        # First declare ORIGINAL Window area        self.myParent = parent        self.myParent.geometry("640x400")        # Layer ONE        ### Our First layer/frame is called frameLayerOne        self.frameLayerOne = Frame(parent, bg="green")        self.frameLayerOne.pack(expand=YES, fill=BOTH)        ### We will stack vertically inside frameLayerOne.        ### Inside frameLayerOne, we will create         ### a menu_frame, then a sub frame into which we will        ### put an output_frame and an input_frame.        # Layer TWO        # MENU FRAME - Layer Two        self.menu_frame = Frame(self.frameLayerOne, borderwidth=5,  relief=RIDGE, bg="cyan")        self.menu_frame.pack(side=TOP, expand=NO,  padx=0, pady=0, ipadx=0, ipady=0, fill=X)        MessageMenuFrame="Menu frame.\n"        # Label(self.menu_frame, text=MessageMenuFrame, justify=LEFT).pack(side=TOP, anchor=W)        # buttons frame        self.buttons_frame = Frame(self.menu_frame) # , bg="red"        self.buttons_frame.pack(side=TOP,            ipadx=buttons_frame_ipadx,            ipady=buttons_frame_ipady,            padx=buttons_frame_padx,            pady=buttons_frame_pady,)        # now we add the buttons to the buttons_frame        self.button1 = Button(self.buttons_frame, command=self.button1Click)        self.button1.configure(text="CONNECT", background= "green")        self.button1.focus_force()        self.button1.configure(width=button_width,            padx=button_padx,            pady=button_pady)        self.button1.pack(side=LEFT)        # T3 - bound to regular button1Click        self.button1.bind("<Return>", self.button1Click)        self.button2 = Button(self.buttons_frame, command=self.button2Click)        self.button2.configure(text="QUIT", background="red")        self.button2.configure(width=button_width,            padx=button_padx,            pady=button_pady)        self.button2.pack(side=RIGHT)        # T3 - bound to regular button2Click        self.button2.bind("<Return>", self.button2Click)        # SUB FRAME - Layer Two        self.sub_frame = Frame(self.frameLayerOne) # , bg="red"        self.sub_frame.pack(side=BOTTOM, expand=YES,  padx=0, pady=0, ipadx=0, ipady=0, fill=BOTH)        # Layer THREE        # INPUT FRAME - Layer Three        self.input_frame = Frame(self.sub_frame, borderwidth=5,  relief=RIDGE, bg="black")        self.input_frame.pack(side=BOTTOM, expand=NO,  padx=0, pady=0, ipadx=0, ipady=0, fill=X)        # Text widget for user input to send to server        self.InputText = Text(self.input_frame, height=4, bg="black", fg="green")        self.InputText.pack()        self.InputText.insert(END, "User input here")        self.InputText.bind('<Return>', self.return_key)        # OUTPUT FRAME - Layer Three        self.output_frame = Frame(self.sub_frame, borderwidth=5,  relief=RIDGE, bg="blue")        self.output_frame.pack(side=BOTTOM, expand=YES,  padx=0, pady=0, ipadx=5, ipady=25, fill=BOTH)        # Text widget for output from code and server        self.OutputText = Text(self.output_frame, bg="black", fg="green")        self.OutputText.pack()        self.OutputText.insert(END, "server and code output here")    def return_key(self, event):        text = "you pressed Return"        self.InputText.insert(END, text)    def button1Click(self, event=None): # T3 - give it a default event of None        if self.button1["background"] == "green":            self.button1["background"] = "yellow"        else:            self.button1["background"] = "green"        self.button1.focus_set() # T3 - set focus to this button so Return works    def button2Click(self, event=None): # T3 - give it a default event of None        self.myParent.destroy()root = Tk()myapp = MyApp(root)root.mainloop()