Self half screen scrolling of "visual-line"

[jk411]

Dashes are edges of window, [C] is cursor placement - it can be anywhere on the very bottom line of window, last line has to be wrapping with only part of it visible

setup:

+-------- text \n text \n more text \n text line \n \n very long [C] line that is wrapped and +------- part of it is not visible... \n

• starting "visual-line" mode causes window to scroll half-screen - wrapped line is window-centered