Specify Double-Click event for a Control in Visual Studio Designer

Question

When you Double-Click on a Control in the Visual Studio Designer, you automatically subscribe to some event and an Event Handler is generated in the code behind file.

Double-Clicking on the following Controls subscribes to the corresponding event

• UserControl - Loaded
• Button - Click
• TextBox - TextChanged
• Grid - No event
  etc.

How is this specified, is it a Visual Studio setting? Can this be overrideen and how can you specify which event you want to link to Double-Click for e.g. a Custom Control?

Thanks

Answer 1

There is a DefaultEventAttribute that controls can specify. The designer knows to read this attribute and uses it to determine which event to use as the default.

[DefaultEvent("DoubleClick")]
public class MyClass {

    public event EventHandler DoubleClick;

}

There is also a DefaultPropertyAttribute which is significantly less useful. It just determines the default property name to select in the property grid when the control is selected in the designer.

Answer 2

If wanting to do this in the editor.
For VS2017 (and beyond I suspect). In Designer:

• Select the control on the form
• In the Properties Window, select the Events icon
• The list of available events for that control will be shown
• Double-click the name of the desired event.

This also works for deleting the auto-generated code. Remove the name of the event handler for that event. It will get removed from the *.designer.cs file. Note that you still need to remove the handler code in the form source.