This is a re-implementation of the loupes (magnifying glass) that Apple uses for text selection. DTLoupeView represents the “magnifying glass” shown when positioning a caret or ranged selection. It has three different styles: the regular round loupe, a ranged selection loupe with an arrow at the bottom and a rectangual loupe without arrow.
The loupe is using it's own private
UIWindow so that it can always stay in front of other views.