Quite often, when I switch from one tab to another, the Firefox window loses focus. This is most notable when I switch and close tabs via keyboard shortcuts. For example, I can be closing a bunch of tabs with Ctrl+w and then suddenly is does not work anymore and I notice that the Firefox windows title is greyed out, indicating that the window lost focus. Alt tabbing or clicking the window regains focus, but this is disruptive to the browsing experience.

There is no particular window or external device that grabs the focus from Firefox, and this does not happen with any other applications, only Firefox. I am on Firefox 45.0.1 on Antegros (Arch) Linux kernel 4.4.5.1-ARCH 64-bit. Any help on how to get Firefox to behave normally and keep focus is appreciated.