The native keyboard scene maintained a separate C++ buffer
(m_win64TextBuffer) for physical keyboard input, which was pushed
to the Flash text field via setLabel(). However, when the user typed
with the on-screen controller buttons, Flash updated its text field
directly through ActionScript without updating the C++ buffer.
This caused a desync: switching back to the physical keyboard would
overwrite any text entered via controller, since m_win64TextBuffer
still held the old value before the controller edits.
Fix: read the current Flash text field into m_win64TextBuffer at the
start of each tick(), before consuming new physical keyboard chars.
This ensures both input methods always operate on the same state.