The size returned by this property is based on the font height and border style of the text box. You can use this property to determine the appropriate size of the text box to ensure that text is properly displayed in the control. The value returned by this property is in pixels.
The value of PreferredHeight represents the minimum height the text box must have in order to display a single line of text without clipping the text on the top or bottom. This value is the same whether the Multiline property is set to true or false.
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)