I have used AppRocket and Launchy in the past, which seem to be either dead or nearly dead now. Those launchers are similar to Find & Run. They used "Alt-Space" as the hotkey to bring them up. So it happens sometimes that I press Alt-Space instead of Break to bring up Find & Run. If no other application takes this shortcut, the system menu of the current application is shown. When I now press ESC to get rid of the menu and then Break Find&Run comes up with the cursor inside the text field but when I type nothing appears inside the text field. I then have to press Break twice once to hide it and once to bring it up again. Then it works as expected.
I don't have to press ESC to produce this behaviour. Even when I press Break while the system menu is showing, I get the same behaviour.