In case of horizontal orientation that is part of track located on the left side from the thumb.
In case of vertical orientation that is part of track located below the thumb.
In case of both thumbs that is part of track located between thumbs.
That class is merged with AppStyling css class igsli_TrackValueH or igsli_TrackValueV depending on orientation of slider.
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