Rewrite of choose mode, both to simplify and tidy the code and to add

some modern features.

Now the common code is in mode-tree.c, which provides an API used by the
three modes now separated into window-{buffer,client,tree}.c. Buffer
mode shows buffers, client mode clients and tree mode a tree of
sessions, windows and panes.

Each mode has a common set of key bindings plus a few that are specific
to the mode. Other changes are:

- each mode has a preview pane: for buffers this is the buffer content
  (very useful), for others it is a preview of the pane;

- items may be sorted in different ways ('O' key);

- multiple items may be tagged and an operation applied to all of them
  (for example, to delete multiple buffers at once);

- in tree mode a command may be run on the selected item (session,
  window, pane) or on tagged items (key ':');

- displayed items may be filtered in tree mode by using a format (this
  is used to implement find-window) (key 'f');

- the custom format (-F) for the display is no longer available;

- shortcut keys change from 0-9, a-z, A-Z which was always a bit weird
  with keys used for other uses to 0-9, M-a to M-z.

Now that the code is simpler, other improvements will come later.

Primary key bindings for each mode are documented under the commands in
the man page (choose-buffer, choose-client, choose-tree).

Parts written by Thomas Adam.

tmux.1

@@ -1339,136 +1339,76 @@ the end of the visible pane.
 The default is to capture only the visible contents of the pane.
 .It Xo
 .Ic choose-client
-.Op Fl F Ar format
-.Op Fl t Ar target-window
+.Op Fl t Ar target-pane
 .Op Ar template
 .Xc
-Put a window into client choice mode, allowing a client to be selected
-interactively from a list.
+Put a pane into client mode, allowing a client to be selected interactively from
+a list.
+The following keys may be used in client mode:
+.Bl -column "Key" "Function" -offset indent
+.It Sy "Key" Ta Sy "Function"
+.It Li "Enter" Ta "Choose selected client"
+.It Li "Up" Ta "Select previous client"
+.It Li "Down" Ta "Select next client"
+.It Li "t" Ta "Toggle if client is tagged"
+.It Li "T" Ta "Tag no clients"
+.It Li "C-t" Ta "Tag all clients"
+.It Li "d" Ta "Detach selected client"
+.It Li "D" Ta "Detach tagged clients"
+.It Li "x" Ta "Detach and HUP selected client"
+.It Li "X" Ta "Detach and HUP tagged clients"
+.It Li "z" Ta "Suspend selected client"
+.It Li "Z" Ta "Suspend tagged clients"
+.It Li "O" Ta "Change sort order"
+.It Li "q" Ta "Exit mode"
+.El
+.Pp
 After a client is chosen,
 .Ql %%
-is replaced by the client
-.Xr pty 4
-path in
+is replaced by the client name in
 .Ar template
 and the result executed as a command.
 If
 .Ar template
 is not given, "detach-client -t '%%'" is used.
-For the meaning of the
-.Fl F
-flag, see the
-.Sx FORMATS
-section.
+.Pp
 This command works only if at least one client is attached.
 .It Xo
-.Ic choose-session
-.Op Fl F Ar format
-.Op Fl t Ar target-window
+.Ic choose-tree
+.Op Fl sw
+.Op Fl t Ar target-pane
 .Op Ar template
 .Xc
-Put a window into session choice mode, where a session may be selected
+Put a pane into tree mode, where a session, window or pane may be chosen
 interactively from a list.
-When one is chosen,
+.Fl s
+starts with sessions collapsed and
+.Fl w
+with windows collapsed.
+The following keys may be used in tree mode:
+.Bl -column "Key" "Function" -offset indent
+.It Sy "Key" Ta Sy "Function"
+.It Li "Enter" Ta "Choose selected item"
+.It Li "Up" Ta "Select previous item"
+.It Li "Down" Ta "Select next item"
+.It Li "t" Ta "Toggle if item is tagged"
+.It Li "T" Ta "Tag no items"
+.It Li "C-t" Ta "Tag all items"
+.It Li ":" Ta "Run a command for each tagged item"
+.It Li "f" Ta "Enter a format to filter items"
+.It Li "O" Ta "Change sort order"
+.It Li "q" Ta "Exit mode"
+.El
+.Pp
+After a session, window or pane is chosen,
 .Ql %%
-is replaced by the session name in
+is replaced by the target in
 .Ar template
 and the result executed as a command.
 If
 .Ar template
 is not given, "switch-client -t '%%'" is used.
-For the meaning of the
-.Fl F
-flag, see the
-.Sx FORMATS
-section.
-This command works only if at least one client is attached.
-.It Xo
-.Ic choose-tree
-.Op Fl suw
-.Op Fl b Ar session-template
-.Op Fl c Ar window-template
-.Op Fl S Ar format
-.Op Fl W Ar format
-.Op Fl t Ar target-window
-.Xc
-Put a window into tree choice mode, where either sessions or windows may be
-selected interactively from a list.
-By default, windows belonging to a session are indented to show their
-relationship to a session.
 .Pp
-Note that the
-.Ic choose-window
-and
-.Ic choose-session
-commands are wrappers around
-.Ic choose-tree .
-.Pp
-If
-.Fl s
-is given, will show sessions.
-If
-.Fl w
-is given, will show windows.
-.Pp
-By default, the tree is collapsed and sessions must be expanded to windows
-with the right arrow key.
-The
-.Fl u
-option will start with all sessions expanded instead.
-.Pp
-If
-.Fl b
-is given, will override the default session command.
-Note that
-.Ql %%
-can be used and will be replaced with the session name.
-The default option if not specified is "switch-client -t '%%'".
-If
-.Fl c
-is given, will override the default window command.
-Like
-.Fl b ,
-.Ql %%
-can be used and will be replaced with the session name and window index.
-When a window is chosen from the list, the session command is run before the
-window command.
-.Pp
-.Fl S
-uses
-.Ar format
-instead of the default session
-format and
-.Fl W
-instead of the default window format.
-For the meaning of
-.Ar format ,
-see the
-.Sx FORMATS
-section.
-.Pp
-This command works only if at least one client is attached.
-.It Xo
-.Ic choose-window
-.Op Fl F Ar format
-.Op Fl t Ar target-window
-.Op Ar template
-.Xc
-Put a window into window choice mode, where a window may be chosen
-interactively from a list.
-After a window is selected,
-.Ql %%
-is replaced by the session name and window index in
-.Ar template
-and the result executed as a command.
-If
-.Ar template
-is not given, "select-window -t '%%'" is used.
-For the meaning of the
-.Fl F
-flag, see the
-.Sx FORMATS
-section.
 This command works only if at least one client is attached.
 .It Xo
 .Ic display-panes
@@ -1498,8 +1438,7 @@ The default
 is "select-pane -t '%%'".
 .It Xo Ic find-window
 .Op Fl CNT
-.Op Fl F Ar format
-.Op Fl t Ar target-window
+.Op Fl t Ar target-pane
 .Ar match-string
 .Xc
 .D1 (alias: Ic findw )
@@ -1517,13 +1456,7 @@ matches only the window name and
 matches only the window title.
 The default is
 .Fl CNT .
-If only one window is matched, it'll be automatically selected,
-otherwise a choice list is shown.
-For the meaning of the
-.Fl F
-flag, see the
-.Sx FORMATS
-section.
+.Pp
 This command works only if at least one client is attached.
 .It Xo Ic join-pane
 .Op Fl bdhv
@@ -3982,13 +3915,27 @@ The buffer commands are as follows:
 .Bl -tag -width Ds
 .It Xo
 .Ic choose-buffer
-.Op Fl F Ar format
-.Op Fl t Ar target-window
+.Op Fl t Ar target-pane
 .Op Ar template
 .Xc
-Put a window into buffer choice mode, where a buffer may be chosen
-interactively from a list.
-After a buffer is selected,
+Put a pane into buffer mode, where a buffer may be chosen interactively from
+a list.
+The following keys may be used in buffer mode:
+.Bl -column "Key" "Function" -offset indent
+.It Sy "Key" Ta Sy "Function"
+.It Li "Enter" Ta "Choose selected buffer"
+.It Li "Up" Ta "Select previous buffer"
+.It Li "Down" Ta "Select next buffer"
+.It Li "t" Ta "Toggle if buffer is tagged"
+.It Li "T" Ta "Tag no buffers"
+.It Li "C-t" Ta "Tag all buffers"
+.It Li "d" Ta "Delete selected buffer"
+.It Li "D" Ta "Delete tagged buffers"
+.It Li "O" Ta "Change sort order"
+.It Li "q" Ta "Exit mode"
+.El
+.Pp
+After a buffer is chosen,
 .Ql %%
 is replaced by the buffer name in
 .Ar template
@@ -3996,11 +3943,7 @@ and the result executed as a command.
 If
 .Ar template
 is not given, "paste-buffer -b '%%'" is used.
-For the meaning of the
-.Fl F
-flag, see the
-.Sx FORMATS
-section.
+.Pp
 This command works only if at least one client is attached.
 .It Ic clear-history Op Fl t Ar target-pane
 .D1 (alias: Ic clearhist )