We present BendDesk, a hybrid interactive desk system that combines a horizontal and a vertical interactive surface via a curve. The system provides seamless touch input across its entire area. We explain scalable algorithms that provide graphical output and multi-touch input on a curved surface. In three tasks we investigate the performance of dragging gestures across the curve, as well as the virtual aiming at targets. Our main findings are: 1) Dragging across a curve is significantly slower than on flat surfaces. 2) The smaller the entrance angle when dragging across the curve, the longer the average trajectory and the higher the variance of trajectories across users. 3) The curved shape of the system impairs virtual aiming at targets.