After using gtk3 programs for a while I'm no longer able to select text in the program using click+drag. Restarting gnome-shell did not fix the issue. Restarting the app did until it reappears after some useage. Epiphany is one of the apps I noticed this problem with. I don't remember if other actions using click+drag are broken as well. The problem appeared in libXi 1.7.1-2 and downgrading back to 1.7.1-1 fixes the issue for me.
*** This bug has been marked as a duplicate of bug 965347 ***