I don’t disagree with your request. Especially about how you can’t really interact with the empty space in the left. Even clicking there doesn’t work.
But wouldn’t your life be a lot easier if you use keyboard shortcuts? Why do you claim it is slower on multiple lines? You can select quickly with a mouse, even if the selection is incomplete, and then use the hotkeys to move.
Or hold shift and hit up and down to quickly select multiple lines. Then use the hotkey. I can’t imagine in any case how that is slower than using the mouse to drag.
Dragging text around with a mouse is - in my not humble opinion - a bad idea, prone to all sorts of human-error.
(Edit: Also, I just discovered in testing, if you 4-click on a line, it does select the new line.)