How to resize the width of left-grid and right-timeline

How to resize the width of left-grid and right-timeline by dragging the coincidence line?
I saw example from official website. It can be easily dragged and stretched,but I cannot do it in my programme. How can I make it in normal version.

Hello,
The functionality to resize columns or to make the whole grid resizable by dragging the grid’s border is available only in the PRO edition of Gantt.