I've used 24x24 .ico icons in a cCjGrid before and those are used at that size on higher DPI monitors. To me it looks like the grid scales down the icon to 16x16 when on a lower DPI monitor. It's not increasing the row height in rows where icons are used to accommodate the 24 pixel height of the icon nor is it picking up the 16x16 icon stored in the same .ico file on the lower DPI monitor.