When set, this image will be displayed along with the button's Text. If the button is Selected, the SelectedImage will be displayed, if set.
Note: If the UltraWebToolbar.ImageDirectory property is set, this path should be relative to the ImageDirectory.
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