By the way I get a similar issue with DDLC, but I have the game redrawn in top left corner:

I experienced this one too myself, however it resolved itself after waiting for several seconds. I wasn't in a menu though, but in game.
This should probably be forwarded to the one who is responsible for the fullscreen modification patch since pretty much all games seem to be affected by this bug.
As a temporary workaround, start the game once, close it and then open a terminal and run
/tmp/proton_run winecfg
and enable "Emulate a virtual desktop" in the graphics tab with your screen resolution.
It does "resolve" itself after waiting a few seconds, but then you got all sorts of other issues such as a glitchy overlay, friends avatars looking different and generally glitchy ingame graphics such as blinking water or buildings that looks like just a shaped shadow without textures.
Could be another bug, but alt-tabbing in and out of the game always triggers this
PROTON_USE_WINED3D11=1`x1 2018-08
Using i3 which got workspaces (like separate desktop with a different group of windows), if I switch back and forth to another workspace, the game window becomes black while only the pointer is working and it copies the top left corner of the other workspace.
The current music continues to play until it ends. Somehow, when stopping steam, it played a second music. :smile: I can't say if the game actually loaded at that point.
I've only tested the issue on main menu and loading screen, because game loading takes some time...
OS: Arch Linux
WM: i3-gaps
Using nouveau driver from mesa (so, no support for Vulkan) with
PROTON_USE_WINED3D11=1Compositor disabled for the game
Steam launched using the steam shell launcher (not steam-native or it gets stuck on installing .NET Framework) from Arch Linux
I understand using WINED3D11 instead of DXVK might not be supported.
Game was displaying fine before switching:
