Frozen columns section has no scrollbar

[sbowers-cgi]

Short description
If my grid has too many frozen columns, there may no longer be a horizontal scrollbar visible to scroll to remaining non-frozen columns.

What is current behavior
As more frozen columns are added to the grid (we allow the user to dynamically change this), they can get to a point where horizontal scroll disappears.

What is desired behavior
Either
a) provide a divider between frozen and non-frozen sections and in each section have scroll bar.
b) similar to toolbar header, have a "right" or "left" arrow that can jump to currently non-visible sections of the grid.

Link to jsfidle/codepan with sample code
...

Steps to reproduce or sample

1. Create a grid that is 500 px wide with 20 columns of equal size.
2. Freeze 15 of those columns and you should no longer see a horizontal scroll.

[mpf82]

Simple reproducer: http://jsfiddle.net/1mn5u0dj/

Based on http://w2ui.com/web/demos/#/grid/27