Form.ActiveForm Property


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Gets the currently active form for this application.

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

public static Form ActiveForm { get; }

Property Value

Type: System.Windows.Forms.Form

A Form that represents the currently active form, or null if there is no active form.

You can use this method to obtain a reference to the currently active form to perform actions on the form or its controls.

If your application is a multiple-document interface (MDI) application, use the ActiveMdiChild property to obtain the currently active MDI child form.

The following code example gets the active form and disables all the controls on the form. The example uses the Controls collection of the form to iterate through each control on the form and disable the controls.

public void DisableActiveFormControls()
    // Create an instance of a form and assign it the currently active form.
    Form currentForm = Form.ActiveForm;

    // Loop through all the controls on the active form.
    for (int i = 0; i < currentForm.Controls.Count; i++)
       // Disable each control in the active form's control collection.
       currentForm.Controls[i].Enabled = false;


for requesting a form. Associated enumeration: UIPermissionWindow.AllWindows.

.NET Framework
Available since 1.1
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