CommonDialog.HelpRequest Event

Definition

Namespace:

System.Windows.Forms

Assembly:

System.Windows.Forms.dll

Source:

CommonDialog.cs

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

C#

public event EventHandler? HelpRequest;

Event Type

EventHandler

Examples

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.

C#

// 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.
    this.ColorDialog1.HelpRequest 
        += 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.");
}

Remarks

For information about handling events, see Handling and Raising Events.

Applies to

See also

• OnHelpRequest(EventArgs)