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CommonDialog.HelpRequest Event

Occurs when the user clicks the Help button on a common dialog box.

Namespace:  System.Windows.Forms
Assembly:  System.Windows.Forms (in System.Windows.Forms.dll)

public event EventHandler HelpRequest

For information about handling events, see Consuming Events.

The following code example demonstrates initializing a ColorDialog object setting the AnyColor, AllowFullOpen properties. The ColorDialog object does not allow the user to set a custom color, but it allows the full set of basic colors to be displayed. By setting the SolidColorOnly property to false, it allows the display of colors that are combinations of other colors on systems with 256 or less colors. The example also shows setting the ShowHelp property and handling a HelpRequest event for a dialog box. To run the example, paste the following code in a form and call the InitializeColorDialog method in the form's constructor or Load method. This example requires that the Click event of the button is connected to the event handler defined in the example.

	// This method initializes ColorDialog1 to allow any colors, 
	// and combination colors on systems with 256 colors or less, 
	// but will not allow the user to set custom colors.  The
	// dialog will contain the help button.
	private void InitializeColorDialog()
		this.ColorDialog1 = new System.Windows.Forms.ColorDialog();
		this.ColorDialog1.AllowFullOpen = false;
		this.ColorDialog1.AnyColor = true;
		this.ColorDialog1.SolidColorOnly = false;
		this.ColorDialog1.ShowHelp = true;
		// Associate the event-handling method with
		// the HelpRequest event.
			+= new System.EventHandler(ColorDialog1_HelpRequest);
	// This method opens the dialog and checks the DialogResult value. 
	// If the result is OK, the text box's background color will be changed 
	// to the user-selected color.
	private void Button1_Click(System.Object sender, System.EventArgs e)
		DialogResult result = ColorDialog1.ShowDialog();
		if (result.Equals(DialogResult.OK))
			TextBox1.BackColor = ColorDialog1.Color;
	// This method is called when the HelpRequest event is raised, 
	//which occurs when the user clicks the Help button on the ColorDialog object.
	private void ColorDialog1_HelpRequest(object sender, System.EventArgs e)

		MessageBox.Show("Please select a color by clicking it. "
           + "This will change the BackColor property of the TextBox.");

.NET Framework

Supported in: 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.