bug#34517: tmm menubar menu items have no effect on Android

bug#34517: tmm menubar menu items have no effect on Android

[Juri Linkov]

Touching the top menu items like “File” opens a file submenu nicely
in tmm's *Completions* buffer.

But touching menu items in its submenu like “New Window on Right”
does nothing.

In GNU Emacs 26.1 (build 1, aarch64-unknown-linux-android)
 of 2019-02-17 built on localhost
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bug#34517: tmm menubar menu items have no effect on Android

[Juri Linkov]

> Touching the top menu items like “File” opens a file submenu nicely
> in tmm's *Completions* buffer.
>
> But touching menu items in its submenu like “New Window on Right”
> does nothing.

I can reproduce this in the latest version 27 on GNU/Linux:
clicking with the mouse on menu items from M-` (tmm-menubar)
has the same effect, i.e. no effect.

bug#34517: tmm menubar menu items have no effect on Android

[Eli Zaretskii]

> From: Juri Linkov <juri@linkov.net>
> Date: Mon, 18 Feb 2019 23:22:03 +0200
> 
> > Touching the top menu items like “File” opens a file submenu nicely
> > in tmm's *Completions* buffer.
> >
> > But touching menu items in its submenu like “New Window on Right”
> > does nothing.
> 
> I can reproduce this in the latest version 27 on GNU/Linux:
> clicking with the mouse on menu items from M-` (tmm-menubar)
> has the same effect, i.e. no effect.

tmm-menubar is supposed to be for when there's no mouse at all, so why
do we expect a mouse click to do anything in that case?

bug#34517: tmm menubar menu items have no effect on Android

[Juri Linkov]

>> > Touching the top menu items like “File” opens a file submenu nicely
>> > in tmm's *Completions* buffer.
>> >
>> > But touching menu items in its submenu like “New Window on Right”
>> > does nothing.
>>
>> I can reproduce this in the latest version 27 on GNU/Linux:
>> clicking with the mouse on menu items from M-` (tmm-menubar)
>> has the same effect, i.e. no effect.
>
> tmm-menubar is supposed to be for when there's no mouse at all, so why
> do we expect a mouse click to do anything in that case?

Smartphones translate screen touch events to click event, so this is
the only way to use menus.  Also the help text of tmm menus says:

  "Click on a completion to select it."

But now I see that tmm relies on completing-read-default
and inserts initial input that gets concatenated with
an item selected by clicking in the *Completions* buffer.

When initial input is deleted manually with e.g. <backspace>
before clicking on a menu item, then tmm works correctly.

So the bug is in completing-read-default and can be reproduced
with a simpler test case:

0. emacs -Q

1. ‘C-h f TAB’ displays a list of completions

2. type a nonexistent function name, i.e. some random text
   in the minibuffer, e.g. “blabla”

3. click on an existing valid completion in the *Completions* buffer,
   e.g. on “append”

4. instead of getting the selected item “append”, it fails with:

   user-error: Symbol’s function definition is void: appendblabla

bug#34517: tmm menubar menu items have no effect on Android

[Juri Linkov]

Stefan, please advise shouldn't selecting a completion from the
*Completions* buffer clear the minibuffer's content before
inserting the selected completion?

>>> > Touching the top menu items like “File” opens a file submenu nicely
>>> > in tmm's *Completions* buffer.
>>> >
>>> > But touching menu items in its submenu like “New Window on Right”
>>> > does nothing.
>>>
>>> I can reproduce this in the latest version 27 on GNU/Linux:
>>> clicking with the mouse on menu items from M-` (tmm-menubar)
>>> has the same effect, i.e. no effect.
>>
>> tmm-menubar is supposed to be for when there's no mouse at all, so why
>> do we expect a mouse click to do anything in that case?
>
> Smartphones translate screen touch events to click event, so this is
> the only way to use menus.  Also the help text of tmm menus says:
>
>   "Click on a completion to select it."
>
> But now I see that tmm relies on completing-read-default
> and inserts initial input that gets concatenated with
> an item selected by clicking in the *Completions* buffer.
>
> When initial input is deleted manually with e.g. <backspace>
> before clicking on a menu item, then tmm works correctly.
>
> So the bug is in completing-read-default and can be reproduced
> with a simpler test case:
>
> 0. emacs -Q
>
> 1. ‘C-h f TAB’ displays a list of completions
>
> 2. type a nonexistent function name, i.e. some random text
>    in the minibuffer, e.g. “blabla”
>
> 3. click on an existing valid completion in the *Completions* buffer,
>    e.g. on “append”
>
> 4. instead of getting the selected item “append”, it fails with:
>
>    user-error: Symbol’s function definition is void: appendblabla

bug#34517: tmm menubar menu items have no effect on Android

[Stefan Monnier]

> Stefan, please advise shouldn't selecting a completion from the
> *Completions* buffer clear the minibuffer's content before
> inserting the selected completion?

No, for example when you complete file name "C-x C-f ~/.e TAB"  the
*Completions* buffer will only show ".emacs" so we should clear the
minibuffer before inserting ".emacs" because that would lose the leading
"~/".  There are other circumstances where trailing text needs to
be preserved.

The completion code handles this with `completion-base-position` which
holds the beginning and end of the text that should be replaced when you
choose an item in *Completions*.

>> 0. emacs -Q
>> 1. ‘C-h f TAB’ displays a list of completions
>> 2. type a nonexistent function name, i.e. some random text
>>    in the minibuffer, e.g. “blabla”

The *Completions* content is now "out of date" compared to the minibuffer.

>> 3. click on an existing valid completion in the *Completions* buffer,
>>    e.g. on “append”

completion-base-position was set at step (1) to cover the empty text
after the prompt, so this empty text (which is now right in front of
"blabla") is replaced with "append" resulting in "appendblabla".

Obviously, the result is not what we want.
Now sure how to change which part, tho.  Maybe instead of
completion-base-position we should store the prefix and suffix strings,
so when you select an entry from *Completions* we just clear the
minibuffer and replace it with (concat prefix selection suffix)?


        Stefan

bug#34517: tmm menubar menu items have no effect on Android

[Juri Linkov]

> Maybe instead of completion-base-position we should store the prefix
> and suffix strings, so when you select an entry from *Completions* we
> just clear the minibuffer and replace it with (concat prefix selection
> suffix)?

The prefix and suffix strings might help.  Not sure whether the
following idea will also work, but maybe using markers in the minibuffer
to keep positions of completion base would help.  Inserting text to the
minibuffer will update these markers that could be used to find
completion base in choose-completion.

bug#34517: tmm menubar menu items have no effect on Android

[Juri Linkov]

found 34517 26.1
fixed 34517 27.0.50
quit

> Touching the top menu items like “File” opens a file submenu nicely
> in tmm's *Completions* buffer.
>
> But touching menu items in its submenu like “New Window on Right”
> does nothing.

I noticed that mouse clicks fail even with xterm-mouse-mode,
so looked again at the problem and fixed it in master by
avoiding inserting initial value to the minibuffer.
Also moved the list of pre-populated menu items to the
list of default values for M-n.  And due to the tradition
of reversing completions in tmm-km-list every release,
reversed it once more.