To get the size of the text held in the clipboard.
INTEGER FUNCTION SIZEOF_CLIPBOARD_TEXT@()
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. On 64-bit systems clipboard sizes of more than
2GB can be determined with SIZEOF_CLIPBOARD_TEXT64@.