The internal construction of Textbox's context menu was modified slightly in order to eliminate display problems in some implementations of the Android operating system. Specifically, the call to "registerForContextMenu" was tweaked in the hopes of eliminating problems in some versions of Android.
Many thanks to one of our astute users, endym, for reporting this error and assisting during troubleshooting/testing. Since I do not own the type of Android device which is plagued by the problem, this help has been invaluable. (endym, can you confirm the problem is now solved on your phone? Thanks.) I'm crossing my fingers.