tmux: Scroll only 5 lines when entering copy-mode

Only scroll 5 lines instead of a full page when entering copy-mode
through the wheel as a full page was too disorienting.

TODO: Pass `WheelUpPane` after entering copy-mode instead of redundantly
executing it's bound command.

Somehow neither of the following worked:

  send -XM WheelUpPane
  send -X WheelUpPane

.config/tmux/tmux.conf

@@ -11,10 +11,12 @@ bind -T copy-mode-vi MouseDragEnd1Pane send -X copy-pipe-no-clear "xclip -se p"
 # https://github.com/neovim/neovim/wiki/FAQ#cursor-shape-doesnt-change-in-tmux
 set -ga terminal-overrides '*:Ss=\E[%p1%d q:Se=\E[ q'
 
-# Scroll up one page when entering copy-mode through the mouse wheel. Also
+# Scroll up 5 lines when entering copy-mode through the mouse wheel. Also
 # discard the `-e` flag passed to copy-mode from the default binding (See below)
 bind -n WheelUpPane \
-	if -F "#{||:#{pane_in_mode},#{mouse_any_flag}}" { send -M } { copy-mode -u }
+	if -F "#{||:#{pane_in_mode},#{mouse_any_flag}}" \
+	{ send -M } \
+	{ copy-mode; send -XN5 scroll-up }
 # Scroll without selecting the pane
 bind -T copy-mode-vi WheelUpPane send -XN5 scroll-up
 # Exit copy-mode when at the bottom. This practically mimics `copy-mode -e` but