将 DataGrid 放在网格中， DockPanel ， ContentControl 或直接在窗口中。一个垂直导向的 StackPanel 将给它的孩子任何垂直的空间，即使这意味着它被渲染出来。

Put the DataGrid in a Grid, DockPanel, ContentControl or directly in the Window. A vertically-oriented StackPanel will give its children whatever vertical space they ask for - even if that means it is rendered out of view.