Has anyone found documentation on UITextField's zooming bubble / magnifying glass?

Question

I need to find more information about this feature, but I haven't found anything in either the Docs or on-line.

I'm trying to do 1 of the following 2 things:

1) Suppress the Magnifying glass and/or the square Editor bubble view which appears when the user will "press and hold" the text field.

2) Perhaps create a subclass of UITextField which can determine the background color of the text when the Magnifying Bubbles appear. Apparently a UITextField with a black background color will still always show a white backgroundcolor when the bubble is being used; rendering white text unreadable.