procedure TForm1.FormCreate(Sender: TObject);
begin
  TMSFMXPlanner1.SelectionAppearance.Fill.Kind := TBrushKind.None;
end;

procedure TForm1.TMSFMXPlanner1AfterDrawCell(Sender: TObject;
  ACanvas: TCanvas; ARect: TRectF; ACol, ARow: Integer; AStartTime,
  AEndTime: TDateTime; APosition: Integer; AKind: TTMSFMXPlannerCacheItemKind);
var
  bmp: TBitmap;
begin
  if (ARow = TMSFMXPlanner1.Selection.EndCell.Row) and (ACol = TMSFMXPlanner1.Selection.EndCell.Col) then
  begin
    bmp := TBitmap.Create;
    bmp.LoadFromFile(''MyImage'');
    try
      ACanvas.DrawBitmap(bmp, RectF(0, 0, bmp.Width, bmp.Height), RectF(ARect.Right - bmp.Width, ARect.Top + (ARect.Height - bmp.Height) / 2,
        ARect.Right, ARect.Top + (ARect.Height - bmp.Height) / 2  + bmp.Height), 1);
    finally
      bmp.Free;
    end;
  end;
end;

procedure TForm1.TMSFMXPlanner1BeforeDrawCell(Sender: TObject;
  ACanvas: TCanvas; ARect: TRectF; ACol, ARow: Integer; AStartTime,
  AEndTime: TDateTime; APosition: Integer; AKind: TTMSFMXPlannerCacheItemKind;
  var AAllow, ADefaultDraw: Boolean);
begin
  if (ARow >= TMSFMXPlanner1.Selection.StartCell.Row) and (ARow <= TMSFMXPlanner1.Selection.EndCell.Row)
    and (ACol >= TMSFMXPlanner1.Selection.StartCell.Col) and (Acol <= TMSFMXPlanner1.Selection.EndCell.Col) then
  begin
    ACanvas.Fill.Assign(TMSFMXPlanner1.SelectionAppearance.Fill);
    ACanvas.Fill.Kind := TBrushKind.Solid;
  end;
end;