Programming Visual Basic .NET

Common Dialog Boxes

There are several classes that implement common dialog boxes, such as color selection and print setup. These classes all derive from the CommonDialog class and, therefore, all inherit the ShowDialog method. The syntax of the ShowDialog method is:

Public Function ShowDialog(  ) As System.Windows.Forms.DialogResult

Calling the ShowDialog method causes the dialog box to be displayed modally, meaning that other windows in the application can’t receive input focus until the dialog box is dismissed. The call is asynchronous, meaning that code following the call to the ShowDialog method isn’t executed until the dialog box is dismissed.

The return value of the ShowDialog method is of type DialogResult (defined in the System.Windows.Forms namespace). DialogResult is an enumeration that defines several values that a dialog box could return. The common dialog boxes, however, return only OK or Cancel, indicating whether the user selected the OK or Cancel button, respectively.

In Visual Studio .NET’s Windows Forms Designer, common dialog boxes are added to forms in much the same way that controls and nonvisual components are. Just select the desired dialog box from the Windows Forms tab of the Toolbox. As with nonvisual components, a representation of the dialog box appears within a separate pane rather than directly on the form that is being designed. The properties of the component can then be set in Visual Studio .NET’s Properties window. The Windows Forms Designer creates ...