UserAgent: Mozilla/5.0 (Windows NT 6.3; Win64; x64; rv:52.0) Gecko/20100101 Firefox/52.0

Steps to reproduce the problem:
1. run in kiosk mode with 
        --disable-translate \
        --disable-infobars \
        --disable-suggestions-service \
        --disable-save-password-bubble \
        --disable-session-crashed-bubble \
        --no-first-run \
        --kiosk \
        --incognito --disable-pinch --overscroll-history-navigation=0 \

2. long tap on touchscreen
3. round 'X' button appears that allow to hack the kiosk system running chromium

What is the expected behavior?
no access to system menus and long tap etc. only the kiosk intranet pages available without access to other browser and OS functions

What went wrong?
circle 'X' button popup which gives hacker access to kiosk browser functions

Did this work before? N/A 

Chrome version: 68.0.3440.75  Channel: stable
OS Version: Ubuntu 16.04
Flash Version: 

 1
down vote

This is controlled by the experimental-fullscreen-exit-ui flag. There is a command line option to turn it on (--enable-experimental-fullscreen-exit-ui), but there is no corresponding option to turn it off. The behavior used to be disabled by default, but that is no longer the case.