One simple way to always see the button is to put it on the left. Having it on the right will draw it off the screen unless the last visible column is perfectly visible without a partical column showing.
this.gridControl1.RowStyles[2].TextAlign = GridTextAlign.Right;
Another option is to use the Border.Margin to move the button in, setting these style properties dynamically in QueryCellInfo. Here is a little sample.
10790_3404.zip