难题：在RichEdit中，从第N个字符插入一个ComboBox后，第N＋1个字符怎样往后移动？

Question

如题

Answer 1

先插入ComboBox,然后从ComboBox选上内容后，ComboBox消失。
两种情况：
1。开始显示ComboBox时，字符往后移
2。ComboBOX消失，字符往后移

Answer 2

//参考如下代码～～
unit Unit1;interfaceuses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, ComCtrls;type
  TForm1 = class(TForm)
    RichEdit1: TRichEdit;
    ComboBox1: TComboBox;
    procedure RichEdit1KeyDown(Sender: TObject; var Key: Word;
      Shift: TShiftState);
    procedure ComboBox1Exit(Sender: TObject);
    procedure ComboBox1KeyDown(Sender: TObject; var Key: Word;
      Shift: TShiftState);
    procedure FormCreate(Sender: TObject);
  private
    { Private declarations }
    FSelStart: Integer;
    FSelLength: Integer;
  public
    { Public declarations }
  end;var
  Form1: TForm1;implementation{$R *.dfm}procedure TForm1.RichEdit1KeyDown(Sender: TObject; var Key: Word;
  Shift: TShiftState);
var
  vPoint: TPoint;
begin
  case Key of
    VK_INSERT: begin
      RichEdit1.Perform(EM_POSFROMCHAR, Integer(@vPoint), RichEdit1.SelStart);
      RichEdit1.SelLength := 0;
      FSelStart := RichEdit1.SelStart;
      ///////
      Canvas.Font.Assign(RichEdit1.SelAttributes);
      FSelLength := 1;
      while Canvas.TextWidth(StringOfChar(#32, FSelLength + 1)) < ComboBox1.Width do
        Inc(FSelLength);
      ///////
      RichEdit1.SelText := StringOfChar(#32, FSelLength);
      ComboBox1.Left := RichEdit1.Left + vPoint.X + 2;
      ComboBox1.Top := RichEdit1.Top + vPoint.Y + 1;
      ComboBox1.Visible := True;
      ComboBox1.SetFocus;
      ComboBox1.DroppedDown := True;
    end;
  end;
end;procedure TForm1.ComboBox1Exit(Sender: TObject);
begin
  RichEdit1.SelStart := FSelStart;
  RichEdit1.SelLength := FSelLength;
  RichEdit1.SelText := ComboBox1.Text;
  RichEdit1.ReadOnly := False;
  ComboBox1.Visible := False;
end;procedure TForm1.ComboBox1KeyDown(Sender: TObject; var Key: Word;
  Shift: TShiftState);
begin
  case Key of
    VK_RETURN: RichEdit1.SetFocus;
    VK_ESCAPE: begin
      ComboBox1.Text := '';
      RichEdit1.SetFocus;
    end;
  end;
end;procedure TForm1.FormCreate(Sender: TObject);
begin
  ComboBox1.Visible := False;
end;end.