use ext 3.4 grid example has a column Move Bug:as the picture below,first picture is the right part of the grid on the beginning of the IE windows display ,the grid column can move,
if the grid out of the windows first display,when I move the IE windows's scroller to the grid out of IE windows display part,the column can't move anymore,

to see the ext-all-debug.js on line 47464 ,the calss gridView has these code:

if (grid.enableColumnMove) {
this.columnDrag = new Ext.grid.GridView.ColumnDragZone(grid, this.innerHd);
this.columnDrop = new Ext.grid.HeaderDropZone(grid, this.mainHd.dom);
}
I gess the drag and drop zone render the DOM on the windows has lose some DOM,
but in Ext 4.1 the BUG was gone,while how can I fix the bug on Ext 3.4?

bug1.JPGbug2.JPG