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ControlDesigner.UpdateDesignTimeHtml Method

Refreshes the design-time HTML markup for the associated Web server control by calling the GetDesignTimeHtml method.

Namespace:  System.Web.UI.Design
Assembly:  System.Design (in System.Design.dll)

public virtual void UpdateDesignTimeHtml()

The UpdateDesignTimeHtml method is called by the design host to update the display of the associated Web server control at design time, such as when the control has been modified. Also, a control designer can call the UpdateDesignTimeHtml method after modifying values of the control to update the display of the control.


If you are calling the ComponentChanged event, or using the PropertyDescriptor object to set properties, the IComponentChangeService interface calls the UpdateDesignTimeHtml method for you.

The following code example demonstrates how to respond to a Click event in a control designer to change the focus between regions in a multi-region control and use the UpdateDesignTimeHtml method to update the appearance of the control in the design host.

This code example is part of a larger example for the EditableDesignerRegion class.

// Handler for the Click event, which provides the region in the arguments.
protected override void OnClick(DesignerRegionMouseEventArgs e)
    if (e.Region == null)

    // If the clicked region is not a header, return
    if (e.Region.Name.IndexOf("Header") != 0)

    // Switch the current view if required
    if (e.Region.Name.Substring(6, 1) != myControl.CurrentView.ToString())
        myControl.CurrentView = int.Parse(e.Region.Name.Substring(6, 1));

.NET Framework

Supported in: 4, 3.5, 3.0, 2.0, 1.1, 1.0

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.