RFE: make non-x11 emacs mouse-aware

[Ryan Johnson]

On 07/10/2012 11:37 AM, Ken Brown wrote:
> On 10/1/2012 5:54 PM, Ken Brown wrote:
>> On 10/1/2012 4:29 PM, Ryan Johnson wrote:
>>> On 01/10/2012 3:20 PM, Ken Brown wrote:
>>>> On 10/1/2012 2:49 PM, Ryan Johnson wrote:
>>>>> Hi all, esp. emacs maintainer(s),
>>>>>
>>>>> I'd like to request that the non-x11 emacs be made mouse aware. Right
>>>>> now, terminal mouse mode is broken in normal emacs because the emacs
>>>>> core doesn't recognize the resulting mouse events. You can use
>>>>> emacs-x11
>>>>> in terminal mode as a heavyweight workaround, but it turns out that
>>>>> mouse awareness is controlled by the src/config.h file created by
>>>>> ./configure:
>>>>>> /* Define if you have mouse support. */
>>>>>> /* #undef HAVE_MOUSE */
>>>>>
>>>>> There doesn't seem to be an explicit configure switch for it (it's
>>>>> enabled indirectly by --with-x11 or --with-ns), but editing directly
>>>>> produced the desired results on a headless linux machine, with no
>>>>> undesirable side effects so far. I see no reason it shouldn't also 
>>>>> work
>>>>> under cygwin.
>>>>
>>>> I'd be happy to do it if I could be sure there were no bad side
>>>> effects.  But I never use emacs-nox, so it isn't easy for me to test
>>>> it on a long-term basis.  Maybe you should build it yourself and
>>>> report back.
>>> As noted, I have tested on a headless linux machine, with no 
>>> problems so
>>> far (several days). There seems to be a clean division between the
>>> window management and the mouse handling code. This makes sense, 
>>> because
>>> the mouse events themselves are handled by keymaps and such, in elisp
>>> land, while the generation of those events is deeper and varies
>>> depending on their source (X11, NS, terminal).
>>>
>>> If you worry that cygwin might behave differently than linux, I could
>>> build emacs locally and test as well, but I don't expect any 
>>> difference.
>>>
>>>> And can you be more specific about what you expect emacs to do with
>>>> mouse events when it's running in a terminal?  I thought mintty
>>>> captured mouse events.  In particular, when I run emacs-x11 under
>>>> mintty, C-h k <mouse-click> produces no response; the cursor stays in
>>>> the minibuffer, and emacs continues to wait for me to press a key.
>>>> Running under X, however, emacs does see the mouse click in that same
>>>> situation.  For another example, if I run emacs-x11 under mintty, I
>>>> can highlight text with the mouse and then paste it with
>>>> shift-insert.  But again it's mintty doing the work, not emacs.
>>> On any emacs, xterm-mouse-mode puts the terminal in mouse-reporting 
>>> mode
>>> and starts watching stdin for the xterm mouse escape sequences: left,
>>> right, scroll, modifier keys, anything the terminal makes available
>>> (most xterm-like terminals intercept shift + mouse, for example). You
>>> can peek in xt-mouse.el to see how mouse escapes are turned into
>>> appropriate mouse events, but that's not really important here. The
>>> issue is that emacs-nox doesn't know what to do with '<mouse-1>' etc
>>> that it suddenly starts receiving. I suppose you could manually wire up
>>> all the various events by hand, but on emacs-x11 they're already there
>>> (even in terminal mode) and terminal-generated mouse events work out of
>>> the box.
>>
>> I didn't know about xterm-mouse-mode.
>>
>> OK, I've built emacs-nox with mouse support, and it works, as far as I
>> can tell.  I'll upload it as a test release after I've tested it a
>> little more.
>
> Before going ahead with this, I decided to ask for comments on the 
> emacs-devel list, to make sure no one could see a downside.  This led 
> to a question about your tests on Linux.  The default on Linux is to 
> provide mouse support in a terminal via GPM (which is not available on 
> Cygwin).  Did you explicitly disable GPM when you built emacs for 
> Linux?  If not, then your tests may not be an accurate indication of 
> what will happen on Cygwin.
I'm sorry, my test machine was actually running Solaris, so GPM was 
definitely disabled... mixed up which VM guest on my laptop I was using, 
sorry. I redid the tests with a non-VM Ubuntu 11 machine, and AFAICT GPM 
is *not* the default, at least with emacs-24.2. Neither HAVE_GPM nor 
HAVE_MOUSE was defined, and (unsurprisingly) mouse clicks under 
xterm-mouse-mode mouse give the error: "<mouse-1> is undefined." 
Manually defining HAVE_MOUSE and recompiling fixed the problem.

In any case, I thought GPM was only useful in console mode? I never use 
the console, even on my VM (ssh all the way).

FYI, I chose that linux machine because it has fast internet and 48 
cores, so the whole download-compile-test-compile-test cycle took about 
5 minutes, vs. something closer to an hour on my cygwin laptop. If you 
need me to build on cygwin, I can do it but not today.

Ryan


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