Scrolls @text_view so that @mark is on the screen in the position indicated by @xalign and @yalign. An alignment of 0.0 indicates left or top, 1.0 indicates right or bottom, 0.5 means center. If @use_align is %FALSE, the text scrolls the minimal distance to get the mark onscreen, possibly not scrolling at all. The effective screen for purposes of this function is reduced by a margin of size