Visual Basic 2005 in a Nutshell, Third Edition

Events and Event Binding | 117

Delegates and

Events

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event argument class that doesn’t convey any specific argument data at all. Those

events that have actual event argument data to convey use for

e a class derived

from System.EventArgs instead.

Control-Related Events

In Windows Forms applications, controls are a veritable smorgasbord of built-in

events. For instance, the TextBox control has events associated with changing the

text in the TextBox, pressing a key while the TextBox has the focus, clicking or

double-clicking on the TextBox with the mouse, moving the mouse over the

TextBox, and more.

The Visual Studio IDE can insert an empty event handler for a control into your

source code, complete with the proper event parameters. Once you have added

the control to the form, access the source code related to the form. Just above the

source code editing area are two drop-down lists. The one to the left provides a

list of all controls placed on the form. The drop-down list to the right presents all

available events that correspond to the control or source selected in the left drop-

down list (Figure 8-1). To add a new event handler, select the control from the list

of controls, then select the desired event from the list of events.

Each control has a default event, such as the Click event for ...