AkaneMail.MailEditorForm.menuEdit_DropDownOpening C# (CSharp) Метод

        private void menuEdit_DropDownOpening(object sender, EventArgs e)
        {
            DoInActiveTextBox(ctrl =>
                {
                    this.menuUndo.Enabled = ctrl.CanUndo;

                    // 検索対象は本文入力のみ
                    var istestBody = ctrl.Name == "textBody";
                    menuFind.Enabled = istestBody;
                    menuReplace.Enabled = istestBody;

                    this.menuSelectAll.Enabled = ctrl.Text.Length > 0;

                    var isctrlSelected = ctrl.SelectionLength > 0;
                    this.menuCut.Enabled = isctrlSelected;
                    this.menuCopy.Enabled = isctrlSelected;
                    this.menuDelete.Enabled = isctrlSelected;
                });

            // クリップボードの内容確認
            this.menuPaste.Enabled = Clipboard.ContainsData(DataFormats.Text);
        }