Share via

Form.TransparencyKey Property


Gets or sets the color that will represent transparent areas of the form.

 property System::Drawing::Color TransparencyKey { System::Drawing::Color get(); void set(System::Drawing::Color value); };
public System.Drawing.Color TransparencyKey { get; set; }
member this.TransparencyKey : System.Drawing.Color with get, set
Public Property TransparencyKey As Color

Property Value

A Color that represents the color to display transparently on the form.


The following example creates a window that has a transparent client region regardless of background color of the form. This example requires that the example method is defined within a form class.

   void InitializeMyForm()
      this->BackColor = Color::Red;
      // Make the background color of form display transparently.
      this->TransparencyKey = BackColor;
public void InitializeMyForm()
    this.BackColor = Color.Red;
    // Make the background color of form display transparently.
    this.TransparencyKey = BackColor;
Public Sub InitializeMyForm()
    BackColor = Color.Red
    ' Make the background color of form display transparently.
    TransparencyKey = BackColor
End Sub


When the TransparencyKey property is assigned a Color, the areas of the form that have the same BackColor will be displayed transparently. Any mouse actions, such as the click of the mouse, that are performed on the transparent areas of the form will be transferred to the windows below the transparent area. For example, if the client region of a form is made transparent, clicking the mouse on that area would send the event notification of the click to any window that is below it. If the color assigned to the TransparencyKey property is the same as any controls on the form, they also will be displayed transparently. For example, if you have a Button control on a form that has its TransparencyKey property set to SystemColors.Control, the control will be displayed transparently unless the BackColor property of the Button control is changed to a different color.

This property is not supported when RightToLeftLayout is true.

Applies to