Mapster32: Sliding tile selection mouse input problem

Forum thread: https://forums.duke4.net/topic/10814-sliding-tiles-selection/page__view__findpost__p__336098

Scrolling to the top or bottom of the tile selection prevents the mouse scrollwheel input from being cleared. This combined with the Mouse1 + Scrollwheel function to directly cycle through tiles in 3D Mode causes the tile selection to shift by 1 to the left or right when it is not supposed to.