Optimize UX after using some functionality from the top menu

[llemeurfr]

When I want to access the ToC, I have to tap the center of the screen to have the top menu appear. Then I tap on ToC, tap on an item of this ToC.

The new page is displayed, but the top menu is still there, and hides the top of the screen. We can optimize the UX by hiding the menu at this point. Same when I open the menu and modifies some display property (e.g. font size).