Fix closing of open files.
Fix closing of open files.

* Files field variable was not used, so removed it
* On closing file, it used the Files field variable instead of
  the CurrentOpenFiles field variable.
* Cleared the Search and History tab controls when closing files.

wkitty42/fpGUI,wkitty42/fpGUI,wkitty42/fpGUI,wkitty42/fpGUI,wkitty42/fpGUI,wkitty42/fpGUI