procedure WMPOpenExt(Name: string; Ext: string; Desc: string);
var
  WMPExt: string;
begin
  WMPOpenPresent(Ext);
  if WMPCount < (WMPOpenMaxChar - 3) then  //minus 3 because you at least need room for a '*.' and mystical char WMP adds
  begin
    if (WMPCount + Length(Ext)) >= WMPOpenMaxChar then Exit;

    if RegQueryStringValue(HKLM, PlayerExts + 'Types', Uppercase(Name), WMPExt) and (WMPExt <> '') then
    begin
      Ext := WMPExt + ';' + Ext;
      WMPCount := WMPCount - Length(WMPExt) - 1;
    end;

    WMPCount := WMPCount + Length(Ext) + 1;
    RegWriteStringValue(HKLM, PlayerExts + 'Types', Uppercase(Name), Ext);
    RegWriteStringValue(HKLM, PlayerExts + 'Descriptions', Uppercase(Name), Desc + ' (' + Ext + ')');
    RegWriteStringValue(HKLM, PlayerExts + 'MUIDescriptions', Uppercase(Name), Desc);
  end;
end;