The value of this property is combined with BaseToolbarItem.Act to derive the image-related property names. For example (using the default values for a "bold" button):
Using this example, if the FileType was changed to ".jpg", ImageName would return "bold.jpg" by default, MouseOverImageName would return "bold_over.jpg" by default, etc.
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