For this assignment, you will be building a basic Shopping List application. The application should have a list with the items displayed, a textbox for adding new items to the list, and four buttons: Add, Remove, Load, and Save.

The Add button takes the contents of the text field (textbox) and adds the item in it to the list. Your code must trim the whitespace in front of or at the end of the input in the text field. Infix whitespace is okay (e.g., honey mustard the trim method will not remove the space between the words honey and mustard.) Also, the text in the textbox should be converted to a lowercase representation (e.g., Honey Ham is converted to honey ham.)

The Remove button removes a selected item from the list. The list should allow the user to select more than one item at a time. If no items are selected when the user clicks this remove button, then the application should pop up a message box saying, Please select an item to delete!

The Load button loads the previously saved grocery list into the list widget on your interface. The Save button saves a copy of the grocery list to a file, named list.txt. If the list.txt file doesnt exist, this operation creates it. If it does exist, it will simply overwrite it.

PLEASE NO JAVASWING OR JOPTION. Thanks.