impossible to activate developer mode

[Peter Pan]

MEIZU MX4, Ubuntu 15.04 (r4)

When trying to activate the devolper mode by clicking on the swithc nothing happens. Somebody told me to set a new password, but when I try to set a new password, nothing happens as well. After setting the new password a click on thebutton "change" doesn't have any effect - a click on the "cancel" button neither. No way to leave the window!

I can close the window only by wipingfrom the right to the middle and pushing it to the top. :-(

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I discovered that this problem as well as the one with the pictures from the gallery I couldn't delet - is valid only if I hold the phone vertical. If I turn it on the side everything works well, even if I tip on exactly the same point on the screen.
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