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ContainerControl.ActiveControl Property

Gets or sets the active control on the container control.

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

'Declaration
<BrowsableAttribute(False)> _
Public Property ActiveControl As Control

Property Value

Type: System.Windows.Forms.Control
The Control that is currently active on the ContainerControl.

Implements

IContainerControl.ActiveControl

ExceptionCondition
ArgumentException

The Control assigned could not be activated.

The ActiveControl property activates or retrieves the active control on the container control.

In order to receive a valid value from this property, the object that calls it must either contain or be contained in the control it is calling. If one form tries to call another form's ActiveControl properties, it will receive an undefined value. In this case, you need to define your own communication mechanism between the forms to pass this data.

The following code example inherits from the ScrollableControl class and implements the IContainerControl interface. Implementation is added to the ActiveControl property and the ActivateControl method.

Imports System
Imports System.Windows.Forms
Imports System.Drawing

   Public Class MyContainerControl
      Inherits ScrollableControl
      Implements IContainerControl 

      Private myActiveControl As Control

      Public Sub New()
         ' Make the container control Blue so it can be distinguished on the form. 
         Me.BackColor = Color.Blue

         ' Make the container scrollable. 
         Me.AutoScroll = True 
      End Sub  

      ' Add implementation to the IContainerControl.ActiveControl property. 
      Public Property ActiveControl() As Control Implements IContainerControl.ActiveControl
         Get 
            Return Me.myActiveControl
         End Get 

         Set 
            ' Make sure the control is a member of the ControlCollection. 
            If Me.Controls.Contains(value) Then 
               Me.myActiveControl = value
            End If 
         End Set 
      End Property 

      ' Add implementation to the IContainerControl.ActivateControl(Control) method.
      public Function ActivateControl(active As Control) As Boolean Implements IContainerControl.ActivateControl
         If Me.Controls.Contains(active) Then 
            ' Select the control and scroll the control into view if needed.
            active.Select()
            Me.ScrollControlIntoView(active)
            Me.myActiveControl = active
            Return True 
         End If 
         Return False 
      End Function  

   End Class

.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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