I see that replies in riot.im/develop/ quote the whole message which might be quite long (multiple lines or a long story). I didn't find any issues about this so posting one. It could be a simple expand/collapse button like the one for spoilers on forums, by default it could display the first 10 words or 100 characters (whichever is bigger) and the user can expand the whole message by clicking a button or ellipsis in the end. That would save the screen space greatly.