Instruction is shown when hovers to that widget

Clearing values in ``explode``, ``pie_items`` and ``pie_items_percentage`` variable were broken (that was my fault when I refactored code). Glad I found it while testing.
**Parent window** was added to the messagebox so that user must click any choice in messagebox and then redirect to the tix.Tk or tix.Toplevel window.
Added functionality to make tix.Tk window disappear when user opens Toplevel window and reappear when user exits the tix.Toplevel window.
Removed **Exit Pie Chart Creator** button because I think its useless as we can do the same thing with X button from the title bar.
**Small window gets pop-up when user hover to the specific widget with some texts. This replaces "Instruction" window.**
Added additional exceptions to prevent program from crashing or to make user know what went wrong.
Changed button name "Make chart with registered values" to "Make Pie-Chart".
Deleted some code which became useless after adding new features.
Clicking image at the main window opens the GitHub repository.
Names of some variables and parameters are changed.
Added image of the program to README.md.
Used tix window instead of Tk window.
Placed buttons one after another.
Deleted "Instructions.txt".
Improved some comments.

README.md

@@ -1,5 +1,7 @@
 # Pie-Chart-Creator
 
+<img src="included_files/main.jpg">
+
 A Python program which creates a pie chart using MatPlotLib and has a GUI created using Tkinter. Feel free to copy and use my code anywhere, just don't forget to credit me!
 
 I would like to thank Ghanteyyy (http://github.com/ghanteyyy) for contributing to this project. This program wouldn't have been so nice without his efforts.

pie_chart_creator.py

@@ -1,80 +1,62 @@
 import os
 import sys
+import webbrowser
 
 try:  # Python 3
-    import tkinter as tk
+    import tkinter.tix as tix
     from tkinter import messagebox
 
 except (ModuleNotFoundError, ImportError):  # Python 2
-    import Tkinter as tk
+    import Tix as tix
     import tkMessageBox as messagebox
 
+import requests
 import matplotlib.pyplot as plt
 
 
-def center_window(window, title):
-    '''This function places any window (either TopLevel or Tk) to the center of the screen'''
+def is_internet():
+    '''Check if you are connected to internet'''
 
-    window.withdraw()
-
-    window.update()
-    window.focus()
-    window.grab_set()
-    window.title(title)
-    window.resizable(0, 0)
-    window.iconbitmap(resource_path('included_files\\icon.ico'))
-
-    width, height = window.winfo_width(), window.winfo_height()
-    window.geometry(f'{width}x{height}+{screen_width - width // 2}+{screen_height - height // 2}')
-    window.deiconify()
-
-
-def change_style(wid):
-    '''Change text styles to bold or italic'''
-
-    italic_index = ('23.0', '23.83')
-    bold_indexs = [('1.0', '1.19'), ('4.0', '4.14'), ('5.4', '5.31'), ('8.4', '8.22'), ('11.4', '11.23'), ('14.4', '14.31'), ('17.4', '17.26'), ('20.4', '20.42')]
-
-    for start, end in bold_indexs:
-        wid.tag_add('b', start, end)
-
-    wid.tag_configure('b', font=('Helvetica', '11', 'bold'))
+    try:
+        requests.get('http://google.com')
+        return True
 
-    wid.tag_add('i', italic_index[0], italic_index[1])
-    wid.tag_configure('i', font=('Helvetica', '11', 'italic'))
+    except requests.ConnectionError:
+        return False
 
-    wid.config(state=tk.DISABLED)
 
+def center_window(_window, title):
+    '''Set position of TopLevel or Tk window to the center of the screen'''
 
-def instructions():
-    '''Show instruction window'''
+    _window.withdraw()
 
-    file_path = resource_path('included_files\\instructions.txt')
+    _window.update()
+    _window.title(title)
+    _window.resizable(0, 0)
+    _window.iconbitmap(resource_path('included_files\\icon.ico'))
 
-    with open(file_path, 'r') as f:
-        contents = f.read().strip('\n')
+    width, height = _window.winfo_width(), _window.winfo_height()
+    _window.geometry(f'{width}x{height}+{screen_width - width // 2}+{screen_height - height // 2}')
 
-    instructions_window = tk.Toplevel(window)
+    _window.deiconify()
 
-    instructions_text_widget_frame = tk.Frame(instructions_window)
 
-    instructions_text_widget = tk.Text(instructions_text_widget_frame, height=26, cursor='arrow')
-    instructions_text_widget.insert('1.0', contents)
-    instructions_text_widget.pack(side=tk.LEFT)
+def open_link(event=None, _window=None):
+    '''Open the github page of the author(NMrocks) in the default browser'''
 
-    instructions_text_widget_frame.pack()
+    if is_internet():
+        window.after(0, lambda: webbrowser.open('http://github.com/NMrocks/Pie-Chart-Creator'))
 
-    instructions_window.after(0, lambda: change_style(instructions_text_widget))
-    instructions_window.after(0, lambda: center_window(instructions_window, 'PCC Instructions'))
-    instructions_window.mainloop()
+    else:
+        messagebox.showerror('ERROR', 'Unable to load page because you are not connected to internet', parent=_window)
 
 
 def append():
     '''Store data given by the user'''
 
     item = item_entry.get().title()
-    explode_ = explode_entry.get().title()
     percentage = percentage_entry.get()
+    explode_ = explode_entry.get().title()
 
     if not item:
         messagebox.showerror('Invalid Input', 'Invalid name of item')
@@ -92,7 +74,7 @@ def append():
             explode.append(0)
 
         for widget in [item_entry, percentage_entry, explode_entry]:
-            widget.delete(0, tk.END)
+            widget.delete(0, tix.END)
 
     else:
         messagebox.showerror('Invalid Percentage', 'Percentage must be in number')
@@ -107,23 +89,24 @@ def show_register():
 
     a = 0
 
-    register_window = tk.Toplevel()
+    window.withdraw()
+    register_window = tix.Toplevel()
 
     if pie_items:
-        added_lbl_1 = tk.Label(register_window, text="Name of item", justify=tk.LEFT)
+        added_lbl_1 = tix.Label(register_window, text="Name of item", justify=tix.LEFT)
         added_lbl_1.grid(row=0, column=0, pady=5)
 
-        added_lbl_2 = tk.Label(register_window, text="Percentage", justify=tk.LEFT)
+        added_lbl_2 = tix.Label(register_window, text="Percentage", justify=tix.LEFT)
         added_lbl_2.grid(row=0, column=1, pady=5)
 
-        added_lbl_3 = tk.Label(register_window, text="Emphasis", justify=tk.LEFT)
+        added_lbl_3 = tix.Label(register_window, text="Emphasis", justify=tix.LEFT)
         added_lbl_3.grid(row=0, column=2, pady=5)
 
         for pie_item in copy_pie_items:
-            appended_lbl1 = tk.Label(register_window, text=f"{pie_item.title()}")
+            appended_lbl1 = tix.Label(register_window, text=f"{pie_item.title()}")
             appended_lbl1.grid(row=a + 1, column=0)
 
-            appended_lbl2 = tk.Label(register_window, text=f"{copy_pie_items_percentage[a]}")
+            appended_lbl2 = tix.Label(register_window, text=f"{copy_pie_items_percentage[a]}")
             appended_lbl2.grid(row=a + 1, column=1)
 
             if copy_explode[a] == 0.1:
@@ -132,21 +115,22 @@ def show_register():
             else:
                 _explode_ = "Disabled"
 
-            appended_lbl3 = tk.Label(register_window, text=f"{_explode_}")
+            appended_lbl3 = tix.Label(register_window, text=f"{_explode_}")
             appended_lbl3.grid(row=a + 1, column=2)
 
             a += 1
 
         appended_lbl2.grid(pady=10)
 
     else:
-        added_lbl_1 = tk.Label(register_window, text="No items added yet. Maybe add some items?")
+        added_lbl_1 = tix.Label(register_window, text="No items added yet. Maybe add some items?")
         added_lbl_1.grid(row=0, column=1, pady=10)
 
-    clear_register_btn = tk.Button(register_window, text="Clear Register", justify='center', bd=1, cursor='hand2', relief=tk.SOLID, command=lambda: clear(register_window))
+    clear_register_btn = tix.Button(register_window, text="Clear Register", justify='center', bd=1, cursor='hand2', relief=tix.SOLID, command=lambda: _clear(register_window))
     clear_register_btn.grid(row=a + 1, column=1, pady=10)
 
     register_window.after(0, lambda: center_window(register_window, 'PCC Register'))
+    register_window.protocol('WM_DELETE_WINDOW', lambda: _exit(register_window))
     register_window.mainloop()
 
 
@@ -163,29 +147,34 @@ def make_chart():
         messagebox.showerror('No data', 'No data were inputed to make pie-charts')
 
 
-def _exit_():
-    '''Quit program'''
+def _exit(_window):
+    '''Destroy Tk window or Toplevel window'''
 
-    if messagebox.askyesno('Exit?', 'Do you really want to exit?\nAll registered values will be lost'):
-        window.destroy()
+    if _window == window:
+        if messagebox.askyesno('Exit', 'Do you really want to exit?'):
+            window.destroy()
 
+    else:
+        _window.destroy()
+        window.deiconify()
 
-def clear(window=None):
+
+def _clear(_window=None):
     '''Clear data from the register'''
 
     if pie_items:
-        if messagebox.askyesno('Clear Register?', 'Do you really want to clear REGISTER?'):
+        if messagebox.askyesno('Clear Register?', 'Do you really want to clear REGISTER?', parent=_window):
             for lists in [pie_items, pie_items_percentage, explode]:
-                del lists[0]
+                lists.clear()
 
     else:
-        messagebox.showinfo('Clear Register?', "No items added yet. Maybe add some items?")
+        messagebox.showinfo('Clear Register', "No items added yet. How about adding some items?", parent=_window)
 
-    if window:
-        window.destroy()
+    if _window:
+        _exit(_window)
 
 
-def left_button_bind(event, window):
+def left_button_bind(event=None):
     '''Focus out from the entry widget when user clicks to any widget'''
 
     if event.widget not in [item_entry, percentage_entry, explode_entry]:
@@ -212,53 +201,61 @@ def resource_path(relative_path):
 
 explode, pie_items, pie_items_percentage = [], [], []
 
-window = tk.Tk()
+window = tix.Tk()
+
 screen_width, screen_height = window.winfo_screenwidth() // 2, window.winfo_screenheight() // 2
 
 for _ in range(8):
     window.columnconfigure(_, weight=1)
     window.rowconfigure(_, weight=1)
 
-pcc_logo = tk.PhotoImage(file=resource_path('included_files\\PCC_Logo.png'))
-pcc_logo_lbl = tk.Label(window, image=pcc_logo)
+pcc_logo = tix.PhotoImage(file=resource_path('included_files\\PCC_Logo.png'))
+pcc_logo_lbl = tix.Label(window, image=pcc_logo, cursor='hand2')
 pcc_logo_lbl.grid(column=1, columnspan=3)
+pcc_logo_lbl.bind('<Button-1>', open_link)
 
-item_entry_lbl = tk.Label(window, text="Name of item:")
+item_entry_lbl = tix.Label(window, text="Name of item:")
 item_entry_lbl.grid(row=1, column=1, sticky="W")
 
-item_entry = tk.Entry(window)
+item_entry = tix.Entry(window)
 item_entry.grid(row=1, column=2, sticky="WE")
 
-percentage_entry_lbl = tk.Label(window, text="Percentage:")
+percentage_entry_lbl = tix.Label(window, text="Percentage:")
 percentage_entry_lbl.grid(row=2, column=1, sticky="W")
 
-percentage_entry = tk.Entry(window)
+percentage_entry = tix.Entry(window)
 percentage_entry.grid(row=2, column=2, sticky="WE")
 
-explode_entry_lbl = tk.Label(window, text="Enable emphasis(Y/N):")
+explode_entry_lbl = tix.Label(window, text="Enable emphasis(Y/N):")
 explode_entry_lbl.grid(row=3, column=1, sticky="W")
 
-explode_entry = tk.Entry(window)
+explode_entry = tix.Entry(window)
 explode_entry.grid(row=3, column=2, sticky="WE")
 
-append_btn = tk.Button(window, text="Add values to register", command=append)
-append_btn.grid(row=4, column=1, sticky="WE", padx=1, pady=1)
+append_btn = tix.Button(window, text="Add values to register", cursor='hand2', command=append)
+append_btn.grid(row=4, column=1, sticky="WE", columnspan=3, padx=1, pady=1)
 
-make_chart_btn = tk.Button(window, text="Make chart with registered values", command=make_chart)
-make_chart_btn.grid(row=7, column=1, columnspan=2, sticky="WE", padx=1, pady=1)
+show_register_btn = tix.Button(window, text="View register", cursor='hand2', command=show_register)
+show_register_btn.grid(row=5, column=1, sticky="WE", columnspan=3, padx=1, pady=1)
 
-clear_btn = tk.Button(window, text="Clear Register", command=clear)
-clear_btn.grid(row=5, column=1, sticky="WE", padx=1, pady=1)
+clear_btn = tix.Button(window, text="Clear Register", cursor='hand2', command=_clear)
+clear_btn.grid(row=6, column=1, sticky="WE", columnspan=3, padx=1, pady=1)
 
-exit_btn = tk.Button(window, text="Exit Pie Chart Creator", command=_exit_)
-exit_btn.grid(row=5, column=2, sticky="WE", padx=1, pady=1)
+make_chart_btn = tix.Button(window, text="Make Pie-Chart", cursor='hand2', command=make_chart)
+make_chart_btn.grid(row=7, column=1, columnspan=3, sticky="WE", padx=1, pady=1)
 
-show_register_btn = tk.Button(window, text="View register", command=show_register)
-show_register_btn.grid(row=4, column=2, sticky="WE", padx=1, pady=1)
+window.bind('<Button-1>', left_button_bind)
+window.protocol('WM_DELETE_WINDOW', lambda: _exit(window))
+window.after(0, lambda: center_window(window, 'Pie Chart Creator'))
 
-instructions_btn = tk.Button(window, text="Read Instructions", command=instructions)
-instructions_btn.grid(row=6, column=1, columnspan=2, sticky="WE", padx=1, pady=1)
+balloon = tix.Balloon(window)
+balloon.bind_widget(item_entry, balloonmsg='Input desire name for your item.')
+balloon.bind_widget(clear_btn, balloonmsg='Clear ALL VALUES from the register.')
+balloon.bind_widget(pcc_logo_lbl, balloonmsg='http://github.com/NMrocks/Pie-Chart-Creator')
+balloon.bind_widget(show_register_btn, balloonmsg='View and Edit items stored in register.')
+balloon.bind_widget(percentage_entry, balloonmsg='Input percentage for the name of your item.')
+balloon.bind_widget(make_chart_btn, balloonmsg='Generate a pie-chart according to the data provided by you.')
+balloon.bind_widget(append_btn, balloonmsg='Add values you have entered in the input fields to the register.')
+balloon.bind_widget(explode_entry, balloonmsg="'Y' enables emphasis whereas 'N' disables it. If enabled some\nspaces will be created between the items in the pie-chart.")
 
-window.bind('<Button-1>', lambda event, window=window: left_button_bind(event, window))
-window.after(0, lambda: center_window(window, 'Pie Chart Creator'))
 window.mainloop()