I filed this bug report with the GNOME Epiphany Browser, and it was suggested to me there that the problem was probably with Webkit. https://bugzilla.gnome.org/show_bug.cgi?id=790130 I am running libwebkit2gtk-4.0-37 ----- When a dropdown list appears (including auto-complete on the URL bar and HTML <select> drop-downs, the list appears in the wrong place, usually on the wrong monitor. On this very page, the Severity and OS: dropdowns appear on my right-most monitor despite the fact that I'm running Epiphany on my middle monitor. I'm not sure if this is a GTK bug or what, but Epiphany isn't the only program that does it. QGIS does it as well, and it's QT-based, I believe. Steps to reproduce: 1) Type something in URL bar Expected behavior: Dropdown box appears just below URL bar Actual behavior Dropdown box appears about 2 feet to the right on the wrong monitor Screenshot: https://imagebin.ca/v/3giRN75CQE5b My set-up: Debian testing running 4.13.0-1 kernel GNOME 3 / wayland / nouveau driver ThinkPad W530 with NVidia Quadro K1000M 3 screens -- internal laptop display, plus two external 2560x1440 displays connected via DisplayPort to a Lenovo docking station