Repro:
1. Cmd + F to open a Find/Change dialog. Don't close the dialog (with Done, or Esc, for example).
2. With the Find/Change dialog still open(which is fine; I plan to use it again shortly), resume typing into the document.
3. Click Cmd + F again. What I expect is that the application focus becomes the Find/Change dialog. But what happens instead is that the Find/Change dialog closes. I can't tell you how many times I end up mistakenly typing content into my document that I think is being entered into the Find/Change dialog instead.

The simple solution here is that Cmd + F (Ctrl + F on Windows) should never close the Find/Change dialog. It should always open the dialog and assign focus to it if it was closed, and just assign focus to it if it was already open.