Investigate why pointer locking doesn't work properly on iOS

This is a bit unfortunate, since while the camera rotates correctly even as a pointer captured by the simulator moves past the screen bounds, it might accidentally e.g. trigger the home indicator, the dock, etc.

Therefore it would be nice if we could find out why pointer locking as specified by the corresponding property in `MiniBlocksViewController` doesn't work as expected.

Start by inspecting the pointer-locking property in MiniBlocksViewController and reproduce the issue on iOS with the simulator pointer moving beyond the screen bounds. Trace why the lock does not prevent interactions with the home indicator or dock, and consider the issue done when the cause is identified and pointer locking behaves as expected.

Written by the indexing model from the issue text.