请查查Delphi提供的源代码。
constructor TDBLookupCombo.Create(AOwner: TComponent);
begin
inherited Create(AOwner);
AutoSize := False;
FFieldLink := TFieldDataLink.Create;
FFieldLink.Control := Self;
FFieldLink.OnDataChange := DataChange;
FFieldLink.OnEditingChange := EditingChange;
FFieldLink.OnUpdateData := UpdateData;
FFieldLink.OnActiveChange := FieldLinkActive;
FBtnControl := TWinControl.Create(Self);
FBtnControl.Width := 17;
FBtnControl.Height := 17;
FBtnControl.Visible := True;
FBtnControl.Parent := Self;
FButton := TComboButton.Create(Self);
FButton.SetBounds(0, 0, FBtnControl.Width, FBtnControl.Height);
[blue]FButton.Glyph.Handle := LoadBitmap(0, PChar(32738));[/blue]
FButton.Visible := True;
FButton.Parent := FBtnControl;
FGrid := TPopupGrid.Create(Self);
FGrid.FCombo := Self;
FGrid.Parent := Self;
FGrid.Visible := False;
FGrid.OnClick := GridClick;
Height := 25;
FDropDownCount := 8;
end;