How to pop up a TComboBox at the current caret position in a TMemo

Problem/Question/Abstract:

I would like to pop up a TComboBox at the caret position on a TMemo when the key that is pressed is a full stop (.). Has anyone got any code for this?

Answer:

unit CBoxInMemo;

interface

uses
  Windows, Classes, Controls, Graphics, Forms, StdCtrls;

type
  TFrmCboxInMemo = class(TForm)
    Button1: TButton;
    Memo1: TMemo;
    Label1: TLabel;
    ComboBox1: TComboBox;
    procedure Button1Click(Sender: TObject);
    procedure ComboBox1Exit(Sender: TObject);
    procedure ComboBox1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  FrmCboxInMemo: TFrmCboxInMemo;

implementation

{$R *.DFM}

procedure TFrmCboxInMemo.Button1Click(Sender: TObject);
var
  clientPos: TPoint;
  lineHeight: Integer;
  tmpFont: TFont;
begin
  GetCaretPos(clientPos);
  {Use the following calculation of line height only if you want your combobox
  to appear below the char position you are referencing.}
  tmpFont := Canvas.Font;
  Canvas.Font := Memo1.Font;
  lineHeight := Canvas.TextHeight('Xy');
  Canvas.Font := tmpFont;
  with ComboBox1 do
  begin
    {Adjustment of Top by lineHeight only necessary if combobox is to appear below line.}
    Top := clientPos.Y + Memo1.Top + lineHeight;
    Left := clientPos.X + Memo1.Left;
    Visible := true;
    SetFocus;
  end;
end;

procedure TFrmCboxInMemo.ComboBox1Exit(Sender: TObject);
begin
  ComboBox1.Visible := false;
end;

procedure TFrmCboxInMemo.ComboBox1Click(Sender: TObject);
begin
  ComboBox1.Visible := false;
end;

end.