Form.FormBorderStyle Property

Gets or sets the border style of the form.

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

public FormBorderStyle FormBorderStyle { get; set; }

Property Value

Type: System.Windows.Forms.FormBorderStyle
A FormBorderStyle that represents the style of border to display for the form. The default is FormBorderStyle.Sizable.

ExceptionCondition
InvalidEnumArgumentException

The value specified is outside the range of valid values.

The border style of the form determines how the outer edge of the form appears. In addition to changing the border display for a form, certain border styles prevent the form from being sized. For example, the FormBorderStyle.FixedDialog border style changes the border of the form to that of a dialog box and prevents the form from being resized. The border style can also affect the size or availability of the caption bar section of a form.

NoteNote

With the Sizable style, it is impossible to resize the window below a certain minimum value, even if you have set ControlBox to false and assigned a zero-length string to Text. Consider working around this by using the SizableToolWindow style instead.

The following code example creates a new instance of a Form and calls the ShowDialog method to display the form as a dialog box. The example sets the FormBorderStyle, AcceptButton, CancelButton, MinimizeBox, MaximizeBox, and StartPosition properties to change the appearance and functionality of the form to a dialog box. The example also uses the Add method of the form's Controls collection to add two Button controls. The example uses the HelpButton property to display a help button in the caption bar of the dialog box.

public void CreateMyForm()
{
   // Create a new instance of the form.
   Form form1 = new Form();
   // Create two buttons to use as the accept and cancel buttons.
   Button button1 = new Button ();
   Button button2 = new Button ();

   // Set the text of button1 to "OK".
   button1.Text = "OK";
   // Set the position of the button on the form.
   button1.Location = new Point (10, 10);
   // Set the text of button2 to "Cancel".
   button2.Text = "Cancel";
   // Set the position of the button based on the location of button1.
   button2.Location
      = new Point (button1.Left, button1.Height + button1.Top + 10);
   // Set the caption bar text of the form.   
   form1.Text = "My Dialog Box";
   // Display a help button on the form.
   form1.HelpButton = true;

   // Define the border style of the form to a dialog box.
   form1.FormBorderStyle = FormBorderStyle.FixedDialog;
   // Set the MaximizeBox to false to remove the maximize box.
   form1.MaximizeBox = false;
   // Set the MinimizeBox to false to remove the minimize box.
   form1.MinimizeBox = false;
   // Set the accept button of the form to button1.
   form1.AcceptButton = button1;
   // Set the cancel button of the form to button2.
   form1.CancelButton = button2;
   // Set the start position of the form to the center of the screen.
   form1.StartPosition = FormStartPosition.CenterScreen;

   // Add button1 to the form.
   form1.Controls.Add(button1);
   // Add button2 to the form.
   form1.Controls.Add(button2);

   // Display the form as a modal dialog box.
   form1.ShowDialog();
}

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 8.1, Windows Server 2012 R2, 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.

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