How to make Tkinter window in full screen while starting

To make a Tkinter window start in full screen mode, you can use the attributes method of the Tk class to set the window to full screen. Here’s a step-by-step guide:

1. Import Tkinter: Start by importing the Tkinter module.
2. Create the main window: Instantiate the Tk class.
3. Set the window to full screen: Use the attributes method with the -fullscreen option.
4. Add any widgets: You can add widgets to the window as usual.
5. Start the Tkinter event loop: Call the mainloop method to run the application.

   import tkinter as tk
   
   def main():
       # Create the main window
       root = tk.Tk()
       
       # Set the window to full screen
       root.attributes('-fullscreen', True)
       
       # Optionally, you can set the window to cover only the primary monitor
       # root.attributes('-zoomed', True)  # This works for maximizing, not full-screen
       
       # Add a label to the window
       label = tk.Label(root, text="Full Screen Mode", font=('Arial', 24))
       label.pack(expand=True)
       
       # Add an exit button to exit full screen
       def exit_fullscreen(event=None):
           root.attributes('-fullscreen', False)
       
       # Bind the Escape key to exit full screen mode
       root.bind("<Escape>", exit_fullscreen)
       
       # Start the Tkinter event loop
       root.mainloop()
   
   if __name__ == "__main__":
       main()

   Explanation:

   1. root.attributes('-fullscreen', True): This line makes the window go full screen.
   2. exit_fullscreen function: This function allows you to exit full-screen mode by pressing the Escape key. You can bind this function to the Escape key with root.bind("<Escape>", exit_fullscreen).
   3. label.pack(expand=True): The label is centered and expands to fill the available space.