Product review (4 stars): Easy fix for slippage complaints.
Easy fix for similar complaints. Purchase anti-skid liner for drawers from your local Target and cut to size. I purchased a roll of black anti-skid liner for about $2.50 and use it under my bathroom rugs, and a variety other places. It is very thin and easy to cut. I even lined the trunk of my BMW with this stuff to prevent groceries and what have you from sliding all over the place. I have used anti-skid liner under car floor mats as well.

So just buy a roll of the color of your choice. Cut four or eight squares (four if you just want it on the top of this product. Eight if you want to prevent skidding on the top and the bottom of this product. Problem solved for about $3.00 and 7 minutes of time.