Alt-F3 (text search) does not work

[Blobson]

According to manual mintty supports following functionality:

Searching in the text and scrollback buffer
Alt-F3 opens a search bar with an input field for a search string. Matches are highlighted in the scrollback buffer. Enter/Shift+Enter find the next/previous position of the match and scrolls the scrollback buffer accordingly. The appearance of the search bar and the matching highlight colours can be customized.
Matching is case-insensitive and ignores combining characters.

But pressing Alt-F3 in fatty does nothing.