ColorDialog.AllowFullOpen Property

When set to false, the associated button in the dialog box is disabled and the user cannot access the custom colors control in the dialog box.

The following example illustrates the creation of new ColorDialog. This example requires that the method is called from within an existing form that has a TextBox and Button placed on it.

private void button1_Click(object sender, System.EventArgs e)
 {
    ColorDialog MyDialog = new ColorDialog();
    // Keeps the user from selecting a custom color.
    MyDialog.AllowFullOpen = false ;
    // Allows the user to get help. (The default is false.)
    MyDialog.ShowHelp = true ;
    // Sets the initial color select to the current text color.
    MyDialog.Color = textBox1.ForeColor ;

    // Update the text box color if the user clicks OK  
    if (MyDialog.ShowDialog() == DialogResult.OK)
        textBox1.ForeColor =  MyDialog.Color;
 }
    

.NET Framework

.NET Framework Client Profile

Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

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

Reference