Form.TopLevel Property


Gets or sets a value indicating whether to display the form as a top-level window.

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

public bool TopLevel { get; set; }

Property Value

Type: System.Boolean

true to display the form as a top-level window; otherwise, false. The default is true.

Exception Condition

A Multiple-document interface (MDI) parent form must be a top-level window.

A top-level form is a window that has no parent form, or whose parent form is the desktop window. Top-level windows are typically used as the main form in an application.

The following code example use the Modal property to determine if a form is displayed as a modal form. If it is not the FormBorderStyle and TopLevel properties are changed to make the form non-top-level form with a tool window border.

private void ShowMyNonModalForm()
	Form myForm = new Form();
	myForm.Text = "My Form";

	// Determine if the form is modal.
	if(myForm.Modal == false)
		// Change borderstyle and make it not a top level window.
		myForm.FormBorderStyle = FormBorderStyle.FixedToolWindow;
		myForm.TopLevel = false;

.NET Framework
Available since 1.1
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