XPastrLen()
 Get the length of the longest string in an Array
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   Function:   XPaStrLen()

               Returns the length of largest string in an Array,
               when supplied to XPdisplay().
               Namely, the ~ characters must be removed..

   Syntax:     XPaStrLen(aStrings) --> nDisplayLenMax

   Arguments:  an Array of Strings

   Returns:    It's Max length when displayed with XPdisplay()

   Usage:      Here's the source code:
               Function XPaStrLen(a)
               /***
               * Return Length of largest String in Array for XPdisplay()
               * ie. remove ~, and return largest string.
               */
               Local nMaxLen := 0
               aEval(a,{|s|nMaxLen:=Max(XPstrLen(s),nMaxLen)})
               Return (nMaxLen)