I am drawing a real time chart. X-axis represents the time which grows continuously. The left most spot always display the current timestamp and the right most is 30 seconds from current.

I want to display the left-most and right-most labels. But it appeared that only when both X values are a multiply of 10 would they both show up. Take the sample code below, if minX grows to 11 and maxX 21, then neither label is displayed. I can force the display of right-most label by changing majorTickStep to maxX. Which axis attributes can be used to display the left-most label? Many thanks,