Hi,There is a work around but not an ideal one.
If you set your system to stretch the desktop across both screens (i.e. not be able to run both monitors independently) then Myriad will see this as a single large desktop and stretch accordingly.
The down side is the split may not be even which means that the Carts and Cart Controls are likely to be split where the monitors join but if you can live with this then give it a bash.