To get the large size of the text held in the clipboard.
INTEGER*8 FUNCTION SIZEOF_CLIPBOARD_TEXT64@()
This routine returns the length of the Windows clipboard text array (CF_TEXT or
CF_OEMTEXT format). The returned length includes a null (CHAR(0)) character
that terminates the string.
Returns the length of the string or zero on failure.
Added to FTN95 at version 8.10