@vkc Middle-click paste is one of those "weird Unix" interaction things that really requires other "weird Unix" things to work well, namely focus-follows-mouse and the concept of an X11-like selection mechanism.

It broke when scrollwheels took over the middle button.

It broke when you slipped while bringing a window to the front, thus causing a selection in *that* other window, and thus losing the selection from the first one that you intended to middle-paste.

I loved it in 1996; not anymore.