http://bugs.winehq.org/show_bug.cgi?id=26863
Summary: Portal 1/2 crashes when linked portal is in view with enabled GLSL [fglrx only]. Product: Wine Version: 1.3.18 Platform: x86-64 OS/Version: Linux Status: UNCONFIRMED Severity: normal Priority: P2 Component: -unknown AssignedTo: wine-bugs@winehq.org ReportedBy: NightNord@gmail.com
Well, that's an old bug, valid even for portal 1: when both portals are placed and you are looking at one of them - game crashes. That's only about GLSL enabled. With GLSL disabled, but with high shader settings portal 2 crashes after few seconds of looking at portal. With lower (medium or low) settings it works well.
No backtrace was ever produced by this bug - it just closes silently. fglrx: 11.3, HD4500.