Components for Delphi and C++ Builder.

procedure TForm.DbGridEhDrawColumnCell(Sender: TObject; const Rect: TRect; DataCol: Integer; Column: TColumnEh;
                                                                                                                                State: TGridDrawState);
{Put on the form a TImageList component with two bitmaps: [-] and [+].
Each bitmap has height = 9 and width = 9.
My TImageList component is named imgCellBtn.}

  var
    ImgIdx : Byte; // Inform the bitmap index of the imgCellBtn : TImageList

    CellBtnRect,
    ValueRect : TRect;
    CellBtnState : Integer;

    DBGrid : TDBGridEh;

begin
  DBGrid := Sender as TDBGridEh;

  with DBGrid do
    begin
      {The CellButton is on the Column with DataCol = 0.}
      if (DataCol = 0) then
        begin
          CellBtnRect := Rect;
          CellBtnRect.Left := Rect.Left + 1;
          CellBtnRect.Top  := Rect.Top + 3;
          CellBtnRect.Height := 9;
          CellBtnRect.Width  := 9;
          Canvas.FillRect(Rect);
          CellBtnState := DFC_BUTTON or DFCS_BUTTONPUSH or DFCS_PUSHED or DFCS_FLAT;
          DrawFrameControl(Canvas.Handle, CellBtnRect, DFC_BUTTON, CellBtnState);
   
          if (gdFocused in State) then
            begin
               {pnlValues is the panel with the values of some fields that I want to show when the cellbutton is pressed.}
              if (pnlValues.Visible) then
                ImgIdx := 0 // [-]
              else
                ImgIdx := 1; // [+]
            end
          else
            ImgIdx := 1; // [+]
   
          {imgCellBtn is  a TImageList with two 9x9 bitmaps: [-] and [+].}
          imgCellBtn.Draw(Canvas, CellBtnRect.Left, CellBtnRect.Top, ImgIdx);
   
          {The value of the Field of DataCol = 0 is drawn.}
          ValueRect := Rect;
          ValueRect.Left := CellBtnRect.Left + CellBtnRect.Width + 1;
          ValueRect.Height := Rect.Height;
          ValueRect.Width := Rect.Width - ValueRect.Left - 1;
   
          DBGrid.DefaultDrawColumnCell(ValueRect, DataCol, Column, State);
        end;
   end;
end;