In most GUI / graphics editing apps, you can constrain a resize operation to operate on both dimensions so the sprite will have the same aspect ratio after the resize, as before. This really needs to be added to NGUI especially now that in NGUI 3 the sprite's own dimensions are used instead of the Sprite transform's dimensions. (Previously I would just use the Unity scale tool and drag the yellow center widget - which I guess I can still do... but it seems maybe no longer recommended to scale widgets that way) I tried Shift-drag, Option-drag, Ctrl-drag, all the usual suspects when dragging the handles on a sprite.