Chrome Version       : 69.0.3497.120
OS Version: 10895.78.0
URLs (if applicable) :
Other browsers tested:
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Video of framebuffer corruption -- the system recovers (failure at 0:07): https://photos.app.goo.gl/2Ybd1qLHGCcdos8K7
Video of framebuffer corruption followed by hard system freeze (failure at 1:03): https://photos.app.goo.gl/dAQ9exeJPrS2s8UEA
Close-up photos of artifacts: https://photos.app.goo.gl/7Mnqi6dS7uvBk3Zh7


What steps will reproduce the problem?
1. Install flatpak in Crostini shell: $ sudo apt-get install flatpak
2. Install GIMP 2.10: $ sudo flatpak install https://flathub.org/repo/appstream/org.gimp.GIMP.flatpakref
3. [optional] sync to exact version installed on my system (unlikely to matter): $ flatpak update --commit 1eb97e2d4cde7778507a4e8097448ba55bd95878006da5c6cc1af2c96e3fa673 org.gimp.GIMP
4. Open application: $ flatpak run org.gimp.GIMP
5. Click on "Windows" entry in menu bar
6. Hover mouse over "Dockable Dialogs" item
7. Hover mouse over an item in the submenu that pops up, e.g., "Selection Editor"
8. Wait until a tooltip appears for the menu item
9. Move mouse to the left or right so it hovers over window underneath the menu, dismissing the tooltip but leaving the menu open
10. GOTO 7 and repeat many, many times


What is the expected result?
The tooltip appears at step 8 and disappears at step 9.


What happens instead of that?
Case 1 (~95% of the time): At step 9, the menu disappears for a frame before reappearing; during this time, it appears for a frame in the bottom-left corner of the screen.
Case 2 (~4% of the time): at step 8, small rectangular corruption artifacts appear on-screen in a repeating diagonal pattern, then disappear after a second.
Case 3 (~1% of the time): case 2, but the system hard freezes while the artifacts are on screen. Requires hard shutdown by holding down power button for several seconds.


Please provide any additional information below. Attach a screenshot if
possible.

Hardware: eve i5

Freeze has occurred at least 5 times overall in 69 stable, and never before that. The video shows freeze while interacting with a Linux program, but has also happened with Android apps and webpages.

In all cases, the crash happened right as I forced some redraw / buffer management operation (e.g., spawning a tooltip in The GIMP; forcing a canvas redraw after scrolling in the Squid Android app).

In all cases, the Crostini subsystem was running at the time, even if I wasn't interacting with a Linux program during the freeze.

Artifacts match https://bugs.chromium.org/p/chromium/issues/detail?id=863747 which also says the problems were caused by menus. Filing new bug because failure mode occurs across Linux and Android apps and has steps to (eventually) reproduce.

UserAgentString: Mozilla/5.0 (X11; CrOS x86_64 10895.78.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/69.0.3497.120 Safari/537.36