A bit non-intuitive for me! When I do a search I get these results and then it opens in a preview box. My natural habit is that the Esc key should close these boxes but that doesn’t work! I randomly spend time using the mouse to click around and it eventually disappears. But not sure what I am doing that it closes.
Please let me know.
An image below to make you understand.
When the extra preview opens, for the first few seconds a status bar shows at the bottom telling you to either click to dismiss the window or to tear it off as a stand-alone window. So, before you close the Find pop-up you need to close the preview. So, either:
I’ve updated my aTbref notes on the Find pop-over to address the issues of the preview pane being open.
Super, wonder why I missed the text which says dismiss this . Maybe ageing eye sight 
Thx!