Help, I can't change size, minimize or maximize darktable window

May be it is not related to darktable itself, but that only happens to me with darktable. The top bar, where the buttons to minimize or change size appear, and that makes it possible to move the window, has disappeared. Any idea of the reason?
I enclose a copy of what I see . Thank you in advance

Press F11 to toggle full-screen mode.

https://darktable-org.github.io/dtdocs/en/overview/user-interface/screen-layout/#panel-size-and-visibility

Yes!!! thanks a lot