I have also this bug with firefox but It's not because of beryl. This bug appear when Composite Option is "Enabled" in xorg.conf and when a composite manager is enabled (like compiz, beryl, xfce composite manager etc...).
I have also this bug with firefox but It's not because of beryl. This bug appear when Composite Option is "Enabled" in xorg.conf and when a composite manager is enabled (like compiz, beryl, xfce composite manager etc...).