Original changes.

tmux.1

@@ -2402,22 +2402,31 @@ The synopsis for the
 command is:
 .Bl -tag -width Ds
 .It Xo Ic copy-mode
-.Op Fl deHMqu
+.Op Fl deHMquS
 .Op Fl s Ar src-pane
 .Op Fl t Ar target-pane
 .Xc
 Enter copy mode.
+.Pp
 .Fl u
-also scrolls one page up after entering and
+enters copy mode and scrolls one page up and
 .Fl d
-one page down if already in copy mode.
-.Fl M
-begins a mouse drag (only valid if bound to a mouse key binding, see
-.Sx MOUSE SUPPORT ) .
+one page down.
 .Fl H
 hides the position indicator in the top right.
 .Fl q
 cancels copy mode and any other modes.
+.Pp
+.Fl M
+begins a mouse drag (only valid if bound to a mouse key binding, see
+.Sx MOUSE SUPPORT ) .
+.Fl S
+scrolls when bound to a mouse drag event; for example,
+.Ic copy-mode -Se
+is bound to
+.Ar MouseDrag1ScrollbarSlider
+by default.
+.Pp
 .Fl s
 copies from
 .Ar src-pane
@@ -5028,6 +5037,55 @@ and
 .Ql heavy
 will fall back to standard ACS line drawing when UTF-8 is not supported.
 .Pp
+.It Xo Ic pane-scrollbars
+.Op Ic off | modal | on
+.Xc
+When enabled, a character based scrollbar appears on the left or right
+of each pane.
+A filled section of the scrollbar, known as the
+.Ql slider ,
+represents the position and size of the visible part of the pane content.
+By default dragging the scrollbar slider up will enter copy mode; in copy
+mode dragging the slider will scroll the pane.
+.Pp
+If set to
+.Ic on
+the scrollbar is visible all the time.
+If set to
+.Ic modal
+the scrollbar only appears when the pane is in copy mode or view mode.
+When the scrollbar is visible, the pane is narrowed by the width of the
+scrollbar and the text in the pane is reflowed.
+If set to
+.Ic modal ,
+the pane is narrowed only when the scrollbar is visible.
+.Pp
+When the
+.Ic mouse
+option is on, clicking above and below the slider pages up and down and dragging
+the slider scrolls the pane.
+.Pp
+See also
+.Xr pane-scrollbar-style
+and the scrollbar mouse events in the
+.Sx MOUSE SUPPORT
+section.
+.Pp
+.It Ic pane-scrollbar-style Ar style
+Set the pane scrollbar style for the currently active pane.
+For how to specify
+.Ar style ,
+see the
+.Sx STYLES
+section.
+Attributes are ignored.
+.Pp
+.It Xo Ic pane-scrollbars-position
+.Op Ic left | right
+.Xc
+Sets which side of the pane to display the pane scrollbars on.  The
+default is right.
+.Pp
 .It Ic window-status-activity-style Ar style
 Set status line style for windows with an activity alert.
 For how to specify
@@ -5400,6 +5458,9 @@ and a location suffix, one of the following:
 .It Li "StatusLeft" Ta "the left part of the status line"
 .It Li "StatusRight" Ta "the right part of the status line"
 .It Li "StatusDefault" Ta "any other part of the status line"
+.It Li "ScrollbarSlider" Ta "the scrollbar slider"
+.It Li "ScrollbarUp" Ta "above the scrollbar slider"
+.It Li "ScrollbarDown" Ta "below the scrollbar slider"
 .El
 .Pp
 The following mouse events are available: