Create a GUI application that allows the user to select a rate category (from a set of radio buttons), and enter the number of minutes of the call into a text field. A dialog box should display the charge for the call.

Using C# in a visual studio form, Create an application. Add  a label and a button to the form. The button’s Click event procedure should add the  number 1 to the contents of a class-level Integer variable named intNumber and then  display the variable’s contents in the label. Code the application. Be sure to enter the  three Option statements above the Public Class clause. Save the solution and then start  and test the application. Next, change the class-level variable to a static variable.

When does a text box’s TextChanged event occur?