The setHeight() method sets DayPilot.Gantt.heightSpec to "Fixed" and applies a new height in pixels.
"Fixed"
DayPilot.Gantt.setHeight(pixels)
pixels (number) - new Gantt chart height in pixels
pixels
gantt.setHeight(400);
DayPilot.Gantt.heightSpec
DayPilot.Gantt Class
Availability of this API item in DayPilot editions: