tlazyCursorChanger based on Barry K method

LazyCursorHelperLabmda.pas

type
  TScopeExitNotifier = class(TInterfacedObject)
  private
    FProc: TProc;
  public
    constructor Create(const AProc: TProc);
    destructor Destroy; override;
  end;

constructor TScopeExitNotifier.Create(const AProc: TProc);
begin
  FProc := AProc;
end;

destructor TScopeExitNotifier.Destroy;
begin
  if Assigned(FProc) then
    FProc;
  inherited;
end;

function MakeScopeExitNotifier(const AProc: TProc): IInterface;
begin
  Result := TScopeExitNotifier.Create(AProc);
end;

function LazyChangeCursorToHourglass: IInterface;
var
  tmpOldCursor: TCursor;
begin 
  tmpOldCursor := Screen.Cursor;
  result := MakeScopeExitNotifier(procedure begin Screen.Cursor := tmpOldCursor; end);
end;