▶/❚❚ in RichEdit control increases font weight in the middle of text and I don't know why

[CYCho]

I found this haphazardly and used it to my benefit. But I'd like to know why and how it works. ❚ (ChrW(10074)) alone had similar effect, but ▶/❚❚ combination was most suitable for my purpose.

#include <GUIConstantsEx.au3>
#include <GuiRichEdit.au3>
#include <WindowsConstants.au3>

Example()

Func Example()
    Local $hGui, $hRichEdit, $iMsg
    $hGui = GUICreate("Example (" & StringTrimRight(@ScriptName, StringLen(".exe")) & ")", 320, 350, -1, -1)
    $hRichEdit = _GUICtrlRichEdit_Create($hGui, "", 10, 10, 300, 220, _
                    BitOR($ES_MULTILINE, $WS_VSCROLL, $ES_AUTOVSCROLL))
    _GUICtrlRichEdit_SetFont($hRichEdit, 11, "Arial")
    _GUICtrlRichEdit_AppendText($hRichEdit, @CRLF & "1. This is text" & @CRLF & "2. ▶/❚❚ This is more text")
    GUISetState(@SW_SHOW)

    While True
        $iMsg = GUIGetMsg()
        Select
            Case $iMsg = $GUI_EVENT_CLOSE
                _GUICtrlRichEdit_Destroy($hRichEdit) ; needed unless script crashes
                ; GUIDelete()   ; is OK too
                Exit
        EndSelect
    WEnd
EndFunc   ;==>Example

 

Edited 7 hours ago by CYCho