In Python, we can bind functions to classes by turning them into methods using the self naming convention. This is a truly wonderful capability of Python, and it allows us to create large systems that are understandable and maintainable.

Sometimes, when we only write short scripts, OOP does not make sense because we find ourselves prepending a lot of variables with the self naming convention and the code gets unnecessarily large when it does not need to be.

Let's first create a Python GUI using tkinter and code it in the waterfall style.

The following code GUI_FallDown.py creates the GUI:

#====================== 
# imports 
#====================== 
import tkinter as tk 
from tkinter import ttk 
from tkinter import messagebox 

#====================== 
# Create instance 
#====================== 
win = tk.Tk()    

#====================== 
# Add a title        
#======================  
win.title("Python GUI") 

#========================= 
# Disable resizing the GUI 
#========================= 
win.resizable(0,0) 

#============================================================= 
# Adding a LabelFrame, Textbox (Entry) and Combobox   
#============================================================= 
lFrame = ttk.LabelFrame(win, text="Python GUI Programming Cookbook") 
lFrame.grid(column=0, row=0, sticky='WE', padx=10, pady=10) 

#============================================================= 
# Labels 
#============================================================= 
ttk.Label(lFrame, text="Enter a name:").grid(column=0, row=0) 
ttk.Label(lFrame, text="Choose a number:").grid(column=1, row=0, sticky=tk.W) 

#============================================================= 
# Buttons click command 
#============================================================= 
def clickMe(name, number): 
    messagebox.showinfo('Information Message Box', 'Hello '+name+  
                        ', your number is: ' + number) 

#============================================================= 
# Creating several controls in a loop 
#============================================================= 
names         = ['name0', 'name1', 'name2'] 
nameEntries   = ['nameEntry0', 'nameEntry1', 'nameEntry2'] 

numbers       = ['number0', 'number1', 'number2'] 
numberEntries = ['numberEntry0', 'numberEntry1', 'numberEntry2'] 

buttons = [] 

for idx in range(3): 
    names[idx] = tk.StringVar() 
    nameEntries[idx] = ttk.Entry(lFrame, width=12, textvariable=names[idx]) 
    nameEntries[idx].grid(column=0, row=idx+1) 
    nameEntries[idx].delete(0, tk.END) 
    nameEntries[idx].insert(0, '<name>') 

    numbers[idx] = tk.StringVar() 
    numberEntries[idx] = ttk.Combobox(lFrame, width=14,
                                      textvariable=numbers[idx]) 
    numberEntries[idx]['values'] = (1+idx, 2+idx, 4+idx, 42+idx, 100+idx) 
    numberEntries[idx].grid(column=1, row=idx+1) 
    numberEntries[idx].current(0) 

    button = ttk.Button(lFrame, text="Click Me "+str(idx+1), 
                        command=lambda idx=idx: clickMe(names[idx].get(), 
                        numbers[idx].get())) 
    button.grid(column=2, row=idx+1, sticky=tk.W)   
    buttons.append(button) 
#====================== 
# Start GUI 
#====================== 
win.mainloop()

When we run the code, we get the GUI and it looks like this:

We can improve our Python GUI by adding tooltips. The best way to do this is to isolate the code that creates the tooltip functionality from our GUI.

We do this by creating a separate class, which has the tooltip functionality, and then we create an instance of this class in the same Python module that creates our GUI.

Using Python, there is no need to place our ToolTip class into a separate module. We can place it just above the procedural code and then call it from below the class code.

The code will look as follows:

#====================== 
# imports 
#====================== 
import tkinter as tk 
from tkinter import ttk 
from tkinter import messagebox 

#----------------------------------------------- 
class ToolTip(object): 
    def __init__(self, widget): 
        self.widget = widget 
        self.tipwindow = None 
        self.id = None 
        self.x = self.y = 0 

#----------------------------------------------- 
def createToolTip(widget, text): 
    toolTip = ToolTip(widget) 
    def enter(event): toolTip.showtip(text) 
    def leave(event): toolTip.hidetip() 
    widget.bind('<Enter>', enter) 
    widget.bind('<Leave>', leave) 

#----------------------------------------------- 
# further down the module we call the createToolTip function 
#----------------------------------------------- 

for idx in range(3): 
    names[idx] = tk.StringVar() 
    nameEntries[idx] = ttk.Entry(lFrame, width=12, textvariable=names[idx]) 
    nameEntries[idx].grid(column=0, row=idx+1) 
    nameEntries[idx].delete(0, tk.END) 
    nameEntries[idx].insert(0, '<name>') 

    numbers[idx] = tk.StringVar() 
    numberEntries[idx] = ttk.Combobox(lFrame, width=14,
                                      textvariable=numbers[idx]) 
    numberEntries[idx]['values'] = (1+idx, 2+idx, 4+idx, 42+idx, 100+idx) 
    numberEntries[idx].grid(column=1, row=idx+1) 
    numberEntries[idx].current(0) 

    button = ttk.Button(lFrame, text="Click Me "+str(idx+1), 
                        command=lambda idx=idx: clickMe(names[idx].get(),  
                        numbers[idx].get()))                      
    button.grid(column=2, row=idx+1, sticky=tk.W)   
    buttons.append(button) 

#----------------------------------------------- 
    # Add Tooltips to more widgets 
    createToolTip(nameEntries[idx], 'This is an Entry widget.')  
    createToolTip(numberEntries[idx], 'This is a DropDown widget.')  
    createToolTip(buttons[idx], 'This is a Button widget.') 
#-----------------------------------------------

Running the code creates tooltips for our widgets when we hover the mouse over them: