Why can't i move & hide the window at the top of my scre

[Walt Disney]

hello, with other versions ( i can;t tell you know which versions ) i could hide the window at the top but now i can;t


I move the window at the bottom and i can hide it half or more if i want to,

so i can read my emails while i'm watching a bit of the film ( i don;t want to resize it )

I can do it the same to the right and to the left but when i move it to the top, i just goes down like there is a wall up there

Any comments?

Greetings