The Scrollbar widget is a horizontal or vertical scrollbar, depending on the value of the orientation property.
Its position and movement are controlled by the adjustment that is passed to or created by Scrollbar. See Adjustment for more details. The value field sets the position of the thumb and must be between lower and upper - page_size. The page_size represents the size of the visible scrollable area. The fields step_increment and page_increment fields are added to or subtracted from the value when the user asks to move by a step (using e.g. the cursor arrow keys or, if present, the stepper buttons) or by a page (using e.g. the Page Down/Up keys).
scrollbar and a subnode for its contents, with subnodes named trough and slider.
│ ╰── slider
The main node gets the style class .fine-tune added when the scrollbar is in 'fine-tuning' mode.
If steppers are enabled, they are represented by up to four additional subnodes with name button. These get the style classes .up and .down to indicate in which direction they are moving.
Other style classes that may be added to scrollbars inside ScrolledWindow include the positional classes (.left, .right, .top, .bottom) and style classes related to overlay scrolling (.overlay-indicator, .dragging, .hovering) .