In Byobu, with split screen, how is it possible to click with my mouse and select multiple lines within the same split screen only and not the whole terminal line? If I try to select text with my mouse, it is selecting the whole terminal line that includes more than one split screens.
I will write here the way I decided to do this.
In order o be able to copy multiple lines with the mouse from a spited window in byobu and not select characters from the borders and other spited windows, I first maximize (zoom) the current window by pressing "Ctr + a z" , and select the multiple lines with the mouse. If i press again the same key sequence the zooming will stop and will have again the window arrangement as before.
(The Alt-F11 proposed by Moning2 will also do the job but you would have changed your windows arrangement because you will have moved the split to a new window.)