如果你不想以模态显示窗口，也许你可以尝试将其显示为ICustomTaskPane，并将其属性DockPosition设置为MsoCTPDockPosition.msoCTPDockPositionFloating：

public void ShowPane(IRibbonControl control)
        {
            if (ExcelDnaUtil.IsInFunctionWizard())
            {
                return;
            }
             // ... other code

            ICustomTaskPane_pane = CustomTaskPaneFactory.CreateCustomTaskPane(typeof(YourWindow), "YourName");
            _pane.DockPosition = MsoCTPDockPosition.msoCTPDockPositionFloating;
        }