I searched. the "xinput" thingy didn't work for me. neither did the "gsettings get org.gnome.desktop.interface gtk-enable-primary-paste" nor installing and configuring "gnome-tweaks" what worked was opening Firefox in "about:config" and setting "middlemouse.paste" to "false" I tried setting the "gsettings" thing to "true" and the "gnome-tweaks" stuff to (middle-click Paste) "enabled" while the Firefox "middlemouse.paste" thing was on "false" and the result was: Middle Click Paste was NOT working. kisses