Hello,

'recentf-open-files' appears not to use tree widgets in my system if I run
it from an emacsclient session.

Steps to reproduce:
 - write test-rf.el, containing
---
(setq recentf-menu-filter #'recentf-arrange-by-dir)
(recentf-mode)
---
 - close all Emacs server instances
 - launch Emacs with 'emacs -q -l /path/to/test-rf.el';
 - do M-x recentf-open-file (note that there have to be some items in the
'recentf-list' for it to work.)
The menu looks like this:
[image: emacs_session.png]
(If the attached image can't be displayed, the menu displays icons
representing files and directories.)

Now,
 - kill Emacs,
 - launch an Emacs daemon with 'emacs -q -l ~/.emacs.d/test-rf.el --daemon',
 - run 'emacsclient -c'
 - type M-x recentf-open-file;
the menu looks like this:
[image: emacsclient_session.png]
(If the attached image can't be displayed, files and directories are
represented by raw text.)

Note that if I remove '(recentf-mode)' from the init file and execute it in
Emacs instead (doesn't matter whether interactively or by evaluating
Elisp), the widgets work even in a client session.

This is is the output of M-x report-emacs-bug from an emacsclient instance:

In GNU Emacs 26.2 (build 1, x86_64-redhat-linux-gnu, GTK+ Version 3.24.8)
 of 2019-04-30 built on buildvm-06.phx2.fedoraproject.org
Windowing system distributor 'Fedora Project', version 11.0.12004000
System Description: Fedora release 30 (Thirty)

Recent messages:
Loading /usr/share/emacs/site-lisp/site-start.d/desktop-entry-mode-init.el
(source)...done
Starting Emacs daemon.
Loading /home/andrea/.emacs.d/recentf...done
Cleaning up the recentf list...done (0 removed)
When done with this frame, type C-x 5 0
Open /home/andrea/.emacs.d/filesets-cache.el
Dialog canceled
Making completion list...

Configured using:
 'configure --build=x86_64-redhat-linux-gnu
 --host=x86_64-redhat-linux-gnu --program-prefix=
 --disable-dependency-tracking --prefix=/usr --exec-prefix=/usr
 --bindir=/usr/bin --sbindir=/usr/sbin --sysconfdir=/etc
 --datadir=/usr/share --includedir=/usr/include --libdir=/usr/lib64
 --libexecdir=/usr/libexec --localstatedir=/var
 --sharedstatedir=/var/lib --mandir=/usr/share/man
 --infodir=/usr/share/info --with-dbus --with-gif --with-jpeg --with-png
 --with-rsvg --with-tiff --with-xft --with-xpm --with-x-toolkit=gtk3
 --with-gpm=no --with-xwidgets --with-modules
 build_alias=x86_64-redhat-linux-gnu host_alias=x86_64-redhat-linux-gnu
 'CFLAGS=-DMAIL_USE_LOCKF -O2 -g -pipe -Wall -Werror=format-security
 -Wp,-D_FORTIFY_SOURCE=2 -Wp,-D_GLIBCXX_ASSERTIONS -fexceptions
 -fstack-protector-strong -grecord-gcc-switches
 -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1
 -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -m64 -mtune=generic
 -fasynchronous-unwind-tables -fstack-clash-protection -fcf-protection'
 LDFLAGS=-Wl,-z,relro
 PKG_CONFIG_PATH=:/usr/lib64/pkgconfig:/usr/share/pkgconfig'

Configured features:
XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND DBUS GSETTINGS GLIB NOTIFY
ACL LIBSELINUX GNUTLS LIBXML2 FREETYPE M17N_FLT LIBOTF XFT ZLIB
TOOLKIT_SCROLL_BARS GTK3 X11 XDBE XIM MODULES THREADS XWIDGETS LCMS2

Important settings:
  value of $LANG: en_GB.UTF-8
  value of $XMODIFIERS: @im=ibus
  locale-coding-system: utf-8-unix

Major mode: Lisp Interaction

Minor modes in effect:
  recentf-mode: t
  tooltip-mode: t
  global-eldoc-mode: t
  eldoc-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message rmc puny seq byte-opt gv
bytecomp byte-compile cconv dired dired-loaddefs format-spec rfc822 mml
mml-sec password-cache epa derived epg epg-config gnus-util rmail
rmail-loaddefs mm-decode mm-bodies mm-encode mail-parse rfc2231
mailabbrev gmm-utils mailheader sendmail rfc2047 rfc2045 ietf-drums
mm-util mail-prsvr mail-utils server recentf tree-widget wid-edit
cl-loaddefs cl-lib easymenu time-date elec-pair mule-util tooltip eldoc
electric uniquify ediff-hook vc-hooks lisp-float-type mwheel term/x-win
x-win term/common-win x-dnd tool-bar dnd fontset image regexp-opt fringe
tabulated-list replace newcomment text-mode elisp-mode lisp-mode
prog-mode register page menu-bar rfn-eshadow isearch timer select
scroll-bar mouse jit-lock font-lock syntax facemenu font-core
term/tty-colors frame cl-generic cham georgian utf-8-lang misc-lang
vietnamese tibetan thai tai-viet lao korean japanese eucjp-ms cp51932
hebrew greek romanian slovak czech european ethiopic indian cyrillic
chinese composite charscript charprop case-table epa-hook jka-cmpr-hook
help simple abbrev obarray minibuffer cl-preloaded nadvice loaddefs
button faces cus-face macroexp files text-properties overlay sha1 md5
base64 format env code-pages mule custom widget hashtable-print-readable
backquote threads dbusbind inotify lcms2 dynamic-setting
system-font-setting font-render-setting xwidget-internal move-toolbar
gtk x-toolkit x multi-tty make-network-process emacs)

Memory information:
((conses 16 100818 5298)
 (symbols 48 21055 1)
 (miscs 40 57 129)
 (strings 32 30148 1255)
 (string-bytes 1 806227)
 (vectors 16 14946)
 (vector-slots 8 511908 9032)
 (floats 8 58 59)
 (intervals 56 291 0)
 (buffers 992 13))