AppGraphics Drop Down List getdropdownlisttext function not working

I have a problem with getdropdownlisttext function causing program to stop and return to the IDE.
I have a similar problem with MultilineTextBoxes, but I will do a seperate post for that.  All the other Appgraphics controls are working fine for me.

Here is an example

! AppGraphics Drop Down Lists example
program DropDownList

use Appgraphics
implicit none

integer :: winMain
integer :: ddlId, ddlEntries

interface
  subroutine ddlCallBack()
  end subroutine ddlCallBack
end interface

  write(*,*) "Drop Down List Test"

  winMain = initwindow(800, 600, title="App Graphics Drop Down List",  closeflag=.TRUE.)
  call setbkcolor(LIGHTGRAY)
  call clearviewport
 
  !! create a dropdown list
  ddlId = createdropdownlist(50, 50, 300, 300, ddlCallBack)

  ddlEntries = insertdropdownlistentry(ddlId, -1, "1 first item" )
  ddlEntries = insertdropdownlistentry(ddlId, -1, "2 second time" )
  ddlEntries = insertdropdownlistentry(ddlId, -1, "3 try again" )
  ddlEntries = insertdropdownlistentry(ddlId, -1, "4 one more" )
  ddlEntries = insertdropdownlistentry(ddlId, -1, "5 another one to go" )
  ddlEntries = insertdropdownlistentry(ddlId, -1, "6 final entry" )
   
  call loop()
   
  call closewindow(winMain)
end program DropDownList

subroutine ddlCallBack()
  use Appgraphics
  implicit none
 
  character(len=5) :: txt  ! for numeric to integer string conversion
  character(len=50) :: ddlSelText !  to hold the selected line of text
  integer :: ddlSel, TextLen, ListId
 
  ListId = getcallbackcontrolid()

  ! check that we get the correct line number
  ddlSel = getdropdownlistselection(ListId)  !! zero based
 
  write(txt, '(i5)' ) ddlSel
  call dlgmessage(DIALOG_INFO, " got ddl Selection (zero based) " // txt)
 
  ! now get the actual text from that line
  TextLen = getdropdownlisttext(ListId, ddlSel, ddlSelText) !***** this is where it crashes
   
  ! check that the length returned makes sense
  write(txt, '(i15)' ) TextLen
  call dlgmessage(DIALOG_INFO, " got TextLen " // txt )
  ! display the line selected
  call dlgmessage(DIALOG_INFO, " drop down item selected " // ddlSelText)
 
end subroutine ddlCallBack

When the program gets to the TextLen = .... line then is just stops and returns to the IDE.
I cant seem to run debug on Appgraphics, a black window opens and the spinner goes around indicating it is doing something, and nothing happens.  That is why I put in the dialog boxe messages to see what is going on.
If I comment out the TextLen =  .... line   then the program runs, but of course the messages are invalid.

Any ideas ?  Why is it only drop down lists that give me this problem ?
I am using SF 3.38 build 4333 and GNU Fortran 14.1.0 on a Windows 10 desktop

Thanks, Robert