Page up and page down should show some context lines
Right now when you press pgup/pgdn it moves by the whole height of the viewport, so if there's a line that's straddling the top edge of the viewport you can't read it without scrolling back a smaller amount. It should scroll the height of the viewport minus the height of one or two lines.
I partially succeeded in solving this myself. I managed to write the code to lower the page step size, but I cannot figure out where to put it. For now, I put it in ChatView::zoomIn, zoomOut, zoomNormal, so when you zoom in or out it lowers the page step size and all is good. But when you first start Quassel the page step size is the full viewport. I'm not familiar with Qt so I'm not sure where to call this code. I've attached my work in progress as a patch on chatview.cpp.