jQuery Grid Plugin - jqGrid

When I only enable refresh, the width of the pager_left area seems to be calculated correctly.

        testGrid.jqGrid('navGrid','#pager', {edit:false,add:false,del:false,refresh:true}, {}, {}, {}, {multipleSearch:true, multipleGroup:true, showQuery: true} );

If I enable another feature like edit, if I hover over the refresh icon most of it is "active" i.e. I get a tool tip, but if I hover the right most part of the refresh icon, the tool tip doesn't opo up and I nothing happens when I click on that part of the icon.

If I also enable add, then the less of the refresh icon is active (unclickable and no tool tip).

With add, edit, delete, search and refresh active: only half of the refresh button is active.

If I enable columnChooser, almost all of the columnChooser icon is inactive.

Looking at the elements in firebug, I can see that pager_left overlaps pager_center so it would seem that pager_center is seeing the mouse events for the area that overlaps.

Heres a screen capture showing the columnChooser icon overlapping the first_pager icon:

Enabling delete and refresh, we can see that the pager_left does get wider but pager_center continues to overlap.

Disabling columnChooser we still see a small overlap between  refresh and first_pager:

I've observed this issue in both internet exploer and firefox. I'm using jqgrid 4.5.4.

Is this a javscript layout problem or something that I'm doing incorrectly?

Thanks.