I run Ubuntu 16.04. On searching Ubuntu Software app for Emacs I am presented with two guis, Lucid and Gtk.

Which one should I choose and why?

  • 1
    Further to Peter's answer, see also here re: stability. I too switched to lucid for increased stability, e.g. when killing X. – Basil May 26 '17 at 14:56

Reasons to use Lucid over GTK


Examples from etc/PROBLEMS:

** When Emacs is compiled with Gtk+, closing a display kills Emacs.

*** Emacs built with GTK+ toolkit produces corrupted display on HiDPI screen
*** Emacs built with GTK+ toolkit can unexpectedly widen frames

Recent example: Bug#25228 "custom-set-faces from init file ~/.emacs ignored" only affects GTK builds.

And generally, new GTK versions could cause breakage, but that's much less of a concern with Lucid.

Also, GTK builds regularly emit scary looking (but harmless??) assertion failures on stderr ;)

Resource consumption

  • top reports 374m virt, 45.5m resident for GTK emacs -Q on startup
  • top reports 340m virt, 31.0m resident for Lucid emacs -Q on startup

Reasons to use GTK over Lucid

Supports some fancier features

It looks nicer

The differences are in the menus, toolbars, and scrollbars (which default to the "wrong" side in Lucid). Lucid screenshot is first (I put the scrollbar on the right side, for easier comparison with GTK).

Screenshot of Lucid build Screenshot of GTK build

PS there is also an option to make a "Motif" build, but (almost) nobody uses that.

| improve this answer | |
  • 1
    I believe the double-buffering fix is for all toolkits: "This extension allows us to reuse our existing drawing code and redirect it to an off-screen buffer. GTK+ or Lucid or Motif or whatever we’re using is oblivious." -- facebook.com/notes/daniel-colascione/buttery-smooth-emacs/… – phils May 27 '17 at 8:46
  • 1
    oh, thanks @phils, I guess since most of that post talks about GTK I somehow got the idea that it was GTK specific. I never saw any flickering personally (apparently I have a "pure soul") so it's all theoretical to me anyway. – npostavs May 27 '17 at 13:05

Lucid Emacs uses the older lucid widget toolkit for XWindows. It looks older and greyer and I see no compelling reason to use it on a modern X desktop. Unless of course you have specific reasons to run it:

  • run emacs in server mode on the background where the lucid version is reportedly more stable
  • run on very stripped down X server configurations

tldr; if you have to ask, stick to Gtk GUI for normal use.

| improve this answer | |
  • 1
    I would be more inclined to say "if you're actually aware that you have a choice, then choose lucid". You might not have encountered problems with GTK (and maybe you never will), but they're a well-known issue, so why risk encountering them in future when you can side-step them completely? – phils May 27 '17 at 8:40

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.