That property has effect only if Location is float.
That class is merged with CssClass and FloatCssClass and AppStyling css class igsli_ValueLabelFloatHover.
Target Platforms: Windows 10, Windows 8.1, Windows 8, Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2