After drag one column not the last column，grid will resizing other column’s width
When scroll to the right,the last column is not visiable.
The last column is missing
Only drag the column back, can the last column be seen.
The image 1 is one of sample from dthtmlx.
The image 2 is after drag the first column.
The image 3 is scrolling to the right,the last column is missing.
All images are from the sample from dhtmlx
Which width settings you have for the third column?
If it is an auto-size (was set as *) - column will take all available free space. And if there is no free space - it will have a zero size.