AkaneMail.MailEditorForm.DoInActiveTextBox C# (CSharp) Method

        private void DoInActiveTextBox(Action<TextBox> action)
        {
            Control ctrl = this.ActiveControl;

            // Spliterコントロール配下のコントロールを取得する
            if (ctrl is SplitContainer) {
                ctrl = (ctrl as SplitContainer).ActiveControl;
                if (ctrl is TextBox) {
                    action(ctrl as TextBox);
                }
            }
        }