Events There is a vast array of event-handling code already available for the hardware buttons and soft keys in the Mobile Device designer. Any time you add a control to an application on the device, you must then specify the event that the control triggers. To add event handling to a button, for example, double-click a button that has been added to a form. Visual Studio automatically opens a page and places the cursor at the insertion point where you can add the relevant code for what you want the button to do when the user clicks it. An event for Button1.