The Marker object class provides the visual representation of a line with a name and depth value displayed. Marker objects are primarily used inside Track widgets. The marker line extends across the entire value direction of the Trackwidget. Visual attributes such as the color and size of the line or the name of the marker are specified using resources from Marker's superclass, the Graphic object class.
The Marker object defines a floating point resource XmNdepth. The Xt library does not support floating point resources, and thus this resource must be passed as an address rather than a value. Floating point resources can also be retrieved using the XtGetValues function. You must specify the address of a pointer to a floating point value in the XtSetArg or XtVaGetValues call. NOTE: This is different from what is done for INT widgets where a special converter is used to make this operation easier.