Size of grid gets smaller when hiding/showing columns

[pikachoo5]

I found a regression bug.
Prior to the upgrade the grid was working fine with 4.0.
Currently I have a grid with many columns, but the columns of interest are two columns with times.
By default column time “EstimatedTime” is visible and column time "ActualTime" is hidden.
I have a check box that when clicked hide/shows column "EstimatedTime" or column "ActualTime".
The issue is that every time I run this code
if (btnRound.is(“:checked”)) {
table.jqGrid(“showCol”, “EstimatedTime”);
table.jqGrid(“hideCol”, “ActualTime”);
} else {
table.jqGrid(“hideCol”, “EstimatedTime”);
table.jqGrid(“showCol”, “ActualTime”);
}
The width of the grid gets smaller. I need the width to stay fixed.

The demo page “New since beta 3.0″ is behaving the same way for “Hide/Show Columns”.
If the user clicks several times the hide and show links, you will notice that the grid is getting smaller.
Thanks any feedback would be appreciated.

[pikachoo5]

I just confirmed the issue happens when the grid has a scroll bar