Scroll.ScrollableSourcetype t = {adj : Adjustment.t;mutable scroll_window_size : Base.int;mutable scroll_bar_mode : Scroll_bar_mode.t;mutable min_scroll_bar_size : Base.int Base.option;mutable max_scroll_bar_size : Base.int Base.option;mutable scroll_bar_size : Base.int;mutable scroll_bar_offset : Base.int;mutable mouse_mode : Mouse_mode.t;mutable page_size : Base.int;mutable document_size : Base.int;mutable on_scrollbar_change : Base.unit -> Base.unit;}