If NullText is not set, then that property has no effect.
Note: It is recommended to set the Width property of editor. Otherwise, visible width of control may jump on focus and blur events, due to italic, bold and other attributes of NullTextCssClass.
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