[Bug 39835] New: Fullscreen Steam popup Flickering

https://bugs.winehq.org/show_bug.cgi?id=39835

Bug ID: 39835
           Summary: Fullscreen Steam popup Flickering
           Product: Wine
           Version: 1.8-rc4
          Hardware: x86-64
                OS: Linux
            Status: UNCONFIRMED
          Severity: minor
          Priority: P2
         Component: -unknown
          Assignee: [e-mail]
          Reporter: [e-mail]
      Distribution: ---

Heyo, so I've been experiencing some screen flickering when I play games in
Wine.
It happens when I get a popup from Steam (Linux version).

To reproduce it.
1. Have Steam (Linux) running.
2. Launch a Wine game in fullscreen.
3. Alt Tab to Steam and get a friend to message you (Game must support alt
tabbing).
4. Quickly go back into the Wine Game and watch the corner where popups appear
at.
5. When friend messages, the screen will flicker.

I've tested it with The Sims 4 and Fallout New Vegas, Origin and Steam
(Windows).

I am on Linux Mint 17.3 running MATE.