Properly handle toggling fullscreen state when another fullscreen state change is in progress.
Fixed bug 2212 - SDL_SetTextInputRect has no effect on iOS

philhassey

Overview: While SDL_SetTextInputRect works perfectly to move my window out of the way of the virtual keyboard using SDL2/Android, on iOS this function has no effect.

Steps to Reproduce: Call SDL_SetTextInputRect with a rect near the bottom of the screen before calling SDL_StartTextInput.

Actual Results: The iOS virtual keyboard is displayed after calling SDL_StartTextInput, but the screen is not shifted to reveal the TextInputRect region.

Expected Results: The screen should be shifted to reveal the TextInputRect region (like with SDL2/Android.)

This patch implements SDL_SetTextInputRect for uikit/iOS.

It sets up notification handlers to respond to changes in the display of the keyboard.  These handlers then change the frame of the view so it is moved out of the way of the keyboard as per SetTextInputRect.