You can use a transparent window (AllowTransparency = True) with a grid, then when your control needs to be hidden you can set the visibility of the control to collapsed. There will be no flickering and no moving of the window but there won't be anything there either so you will see throug as if you would have resized, moved your window.
某些时候，弹出的窗体会闪烁，这着实让人难受，通过给要弹出的窗体设置AllowTransparency为True，对闪烁问题有一定的缓解。
2021.01.19 补充
某些情况下，设置窗体的ResizeMode="NoResize" 也能缓解闪烁问题