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type
  TIsThemeActive = function: bool; stdcall;

var
  IsThemeActive  : TIsThemeActive;
  xpthemedll     : dword = 0;

begin
  xpthemedll := GetModuleHandle('uxtheme.dll');
  if(xpthemedll = 0) then xpthemedll := LoadLibrary('uxtheme.dll');

  if(xpthemedll <> 0) then begin
    @IsThemeActive := GetProcAddress(xpthemedll,'IsThemeActive');

    if(@IsThemeActive = nil) then begin
      FreeLibrary(xpthemedll);
      xpthemedll := 0;
    end;
  end;
end;