I've noticed lately when playing through Proton, when I try to move the cursor out of some games to my second monitor it snaps back once. After that, it leaves the screen properly as long as the cursor is still visible. It happens again if the cursor has gone back to not being visible.
Those games experience this with Proton 7.0-6, Proton 8.0-2, Proton Experimental, Proton Experimental bleeding-edge, and Proton GE.
I used a clean prefix each time I changed Proton versions. The cursor leaves the window without issue every time on an X11 session.
Some games I've found it happening with are Monster Hunter Rise, Deep Rock Galactic, Project Wingman. They were all set to Borderless, but it happens with Fullscreen as well.
When I tried Earth Defense Force 5 in Fullscreen, it didn't happen with any Proton version. That game only has Windowed and Fullscreen.
I don't know if any of these games are expecting the cursor to be locked to the window to begin with. . .
I've also found that in DRG, sliders in options change the cursor to the desktop environment's, which when clicked and held jumps to a far side of the window in a similar fashion.
OS: Fedora 38 KDE
KDE Plasma Version: 5.27.5
KDE Frameworks Version: 5.107.0
Qt Version: 5.15.10
Kernel: 6.3.8
Mesa Version: 23.1.2
GPU: RX 6700 XT
I've noticed lately when playing through Proton, when I try to move the cursor out of some games to my second monitor it snaps back once. After that, it leaves the screen properly as long as the cursor is still visible. It happens again if the cursor has gone back to not being visible.
Those games experience this with Proton 7.0-6, Proton 8.0-2, Proton Experimental, Proton Experimental bleeding-edge, and Proton GE.
I used a clean prefix each time I changed Proton versions. The cursor leaves the window without issue every time on an X11 session.
Some games I've found it happening with are Monster Hunter Rise, Deep Rock Galactic, Project Wingman. They were all set to Borderless, but it happens with Fullscreen as well.
. 
.
When I tried Earth Defense Force 5 in Fullscreen, it didn't happen with any Proton version. That game only has Windowed and Fullscreen.
I don't know if any of these games are expecting the cursor to be locked to the window to begin with.
I've also found that in DRG, sliders in options change the cursor to the desktop environment's, which when clicked and held jumps to a far side of the window in a similar fashion.
OS: Fedora 38 KDE
KDE Plasma Version: 5.27.5
KDE Frameworks Version: 5.107.0
Qt Version: 5.15.10
Kernel: 6.3.8
Mesa Version: 23.1.2
GPU: RX 6700 XT