Classic CRT Computer Displays They had rounded corners due to the ray scan was from a single point and it makes an ellipse. LCD/LED Displays Perfectly rectangular due to pixels are squares UI have changed into utilising corners and usually have icons or those kinds of stuff there. Modern Mobile Displays Lots are having rounded corners now Fits something about near future of 3D projection below. Near Future 3D Projection Seems to have rounded corners and even blurry rim. UI should cha...