Hand-apply 9a90f25eb891d7d590563c0ce1597de4da8ff575; bind to

Hand-apply 9a90f25eb891d7d590563c0ce1597de4da8ff575; bind to
wxEVT_COMMAND_TEXT_UPDATED as well as wxEVT_COMMAND_SPINCTRL_UPDATED
on the JPEG2000 control otherwise entering a value using the keyboard
directly before doing "Make DCP" can seemingly result in the new value
not being read in until after the video MXF filename has been decided.
This results in a file not found at the end of the encode.