win32 interfacing check (SetClipboardData)

[Xavier Petit <le@vieux.pro>]

Hi, I would like to know if this win32 code is “correct” from your PoV 
or could be written in a better way, especially this block :

declare
    Tmp : Wide_String (1 .. Source'Length + 1) with Address => AMem;
begin
    Tmp := Source & Wide_Character'First;
end;

Complete code : https://pastebin.com/raw/CnUbGVyk

It copies the Source Wide_String in the Windows clipboard and needs 
Win32Ada & -gnatW8 -gnata compilation flags (in order to get correct 
unicode characters and assertions enabled)

Thanks by advance

-- 
Xavier Petit