I am at a loss to understand why when navigating in Sketchup you are suddenly navigating trough heavy mud with the mouse and getting muscle burn with the ineffectual center wheel but as I grab my 3d Dexion "mouse" with my left hand the mud is gone and easy navigation returns. Surely this is an issue with the mouse/SKP navigation if the issue disappears with another navigation interface Surely this can be fixed in 2016