Often the visual representation of an object, such as a document or a list, will not fit within the space allocated to its viewer control. In these cases, scrollbars can be attached to the viewer control. These allow the user to alter the horizontal or vertical position of the viewport onto the object, and thus the portion of the object that is visible.
Guidelines
Only display scrollbars when they are required. If
an object fits entirely inside the viewer control, don't draw scrollbars. If you are
using a GtkScrolledWindow, use gtk_scrolled_window_set_policy
to set the scrollbar display policy to GTK_POLICY_AUTOMATIC.
Affix scrollbars to the right or bottom edges only of a viewer control. Make the scrollbar the full height or width of the control.
Update the view in real time as the user drags a scrollbar. Any delay will negatively impact a user's ability to navigate the content.
Don't use a scrollbar as a replacement for a slider.