OT: X11: how to make cut-and-paste with mouse also work on every window

[Ranjan Maitra]

Hi,

I know this is OT, but someone here might know the answer to this.

So, I like the ability to highlight with my mouse left button, and paste with my middle (scroll) button. It works on `xterm` but not necessarily on my firefox window (some other windows too, but I do not recall now). Is there a way to set this up so that it can work reliably on every window?

Many thanks and best wishes,
Ranjan