TextField.InsertionPosAtXY(X,Y)

With this code in a mousedown event

a Window with textfield1, textarea1, and textarea2
textfiield1 & textarea1 both have a string displayed
This code in mouse down event for textfield1 and textarea1

If Not TargetLinux Then
  me.SelStart = me.InsertionPosAtXY(X,Y)  //Click at beg of string returns 0
Else  //linux
  me.SelStart = me.InsertionPosAtXY(X,Y) + 1  //Click at beg of string returns -1
End if
me.SelLength = 1

TextArea2.AppendText  me.SelText

Works correctly in Windows for both textfield and textarea, but only works for textarea on Linux
Without a current license I can’t submit a feedback about this.

This relates to my question.
I am working on Linux just using Windows as a test to see if it works somewhere.

Is there a way to implement the behavior above for a cell in a list box?
Have tried for both Windows and Linux.
I have tried this in several list box events, but have only received p = 0 .

dim p as Integer = lstbox.ActiveCell.InsertionPosAtXY (x, y)

This code in the cellclick event:

Me.CellType(row, column) = Listbox.TypeEditableTextField //same result with textarea here
Me.EditCell(row, column)
mEditRow = row
mEditCol = column
me.Selected(row) = false
return true

Any help would be greatly appreciated
Terry