procedure TformMain.IEColorPalette1CellClick(Button: TMouseButton; 
    Shift: TShiftState; Index: Integer; aColor: TColor; 
    var Allow: Boolean; var CellChar: Char);
begin
  if Button = mbLeft then
    CellChar := 'F' 
  else if Button = mbRight then
    CellChar := 'B'
  else
    CellChar := '';
end;

// Draw an "F" on the foreground color, and a "B" on background color
procedure TMainForm.IEColorPalette1AfterPaintCell(ACanvas: TCanvas; CellRect: TRect;
    aColor: TColor; Index: Integer; aState: TIEColorCellState; var aStyle:
    TIETransparentStyle; var Handled: Boolean);
var
  cellChar: string;
begin
  cellChar := '';
  if aColor = fForegroundColor then
    cellChar := 'F'
  else
  if aColor = fBackgroundColor then
    cellChar := 'B';

  if cellChar <> '' then
  begin
    ACanvas.Brush.Style := bsClear;
    ACanvas.Font.Style := [ fsBold ];

    // Draw text in center of cell
    ACanvas.TextOut( CellRect.Left + ( CellRect.Right - CellRect.Left ) div 2 - ACanvas.TextWidth( cellChar ) div 2,
                     CellRect.Top + ( CellRect.Bottom - CellRect.Top ) div 2 - ACanvas.TextHeight( cellChar ) div 2,
                     cellChar );
  end;
end;