For me, copying into Firefox can lock it up, and trying to paste from Firefox into non-Firefox can also lock it up. I tried looking into this, and it might be r

For me, copying into Firefox can lock it up, and trying to paste from Firefox into non-Firefox can also lock it up. I tried looking into this, and it might be related to running X apps side-by-side, but it feels like a weird interaction between Firefox and gnome-shell. Regardless, it seems like other applications are working fine, so I think this is an issue with Firefox.