This property does not render for all controls in browsers earlier than Microsoft Internet Explorer version 4. Controls that do not render this property in earlier browsers include System.Web.UI.WebControls.Label, System.Web.UI.WebControls.HyperLink, System.Web.UI.WebControls.LinkButton, and any validation controls. The System.Web.UI.WebControls.CheckBoxList, System.Web.UI.WebControls.RadioButtonList and System.Web.UI.WebControls.DataList also do not render this property in earlier browsers when their RepeatLayout property is set to RepeatLayout.Flow. Furthermore, only unit types of Pixel and Percentage are supported in earlier browsers.

To set the WebControl.Width property declaratively to a unit type other than the default of Pixel, you must create a new unit type specific to the unit type you want. For example, to set a control's WebControl.Width property to a percentage value of 100, you could do the following:

myWebControl.width = Unit.Percentage(100);

For more information on the unit types available for the WebControl.Width property, see the System.Web.UI.WebControls.Unit class.