+@vindex scroll-bar-adjust-thumb-portion
+@cindex overscrolling
+If you're using Emacs on X (with GTK+ or Motif), you can customize the
+variable @code{scroll-bar-adjust-thumb-portion} to control
+@dfn{overscrolling} of the scroll bar, i.e. dragging the thumb down even
+when the end of the buffer is visible. If its value is
+non-@code{nil}, the scroll bar can be dragged downwards even if the
+end of the buffer is shown; if @code{nil}, the thumb will be at the
+bottom when the end of the buffer is shown. You can not over-scroll
+when the entire buffer is visible.
+
+@cindex scroll-bar face
+ The visual appearance of the scroll bars is controlled by the
+@code{scroll-bar} face.
+
+@cindex Horizontal Scroll Bar
+@cindex Horizontal Scroll Bar mode
+ On graphical displays with toolkit support, Emacs may also supply a
+@dfn{horizontal scroll bar} on the bottom of each window. Clicking
+@kbd{Mouse-1} on the that scroll bar's left and right buttons scrolls
+the window horizontally by one column at a time. Clicking @kbd{Mouse-1}
+on the left or right of the scroll bar's inner box scrolls the window by
+four columns. Dragging the inner box scrolls the window continuously.
+
+ Note that such horizontal scrolling can make the window's position of
+point disappear on the left or the right. Typing a character to insert
+text or moving point with a keyboard command will usually bring it back
+into view.
+
+@findex horizontal-scroll-bar-mode
+ To toggle the use of horizontal scroll bars, type @kbd{M-x
+horizontal-scroll-bar-mode}. This command applies to all frames,
+including frames yet to be created. To toggle horizontal scroll bars
+for just the selected frame, use the command @kbd{M-x
+toggle-horizontal-scroll-bar}.
+
+@vindex horizontal-scroll-bar-mode
+ To control the use of horizontal scroll bars at startup, customize the
+variable @code{horizontal-scroll-bar-mode}.
+
+@vindex scroll-bar-height
+@cindex height of the horizontal scroll bar
+ You can also use the X resource @samp{horizontalScrollBars} to enable
+or disable horizontal scroll bars (@pxref{Resources}). To control the
+scroll bar height, change the @code{scroll-bar-height} frame parameter
+(@pxref{Frame Parameters,,, elisp, The Emacs Lisp Reference Manual}).
+