Bug#711139: gnuplot-qt: the grid doesn't work with the 'qt' terminal in -persist state

[Vincent Lefevre]

Control: forcemerge 711139 711141

I'm merging these two bugs because they basically cover the same issue.
However each covers 3 different issues: a documentation one, an UI one,
and a feature one (see below).

On 2014-06-10 19:04:42 -0700, sfeam wrote:
> > Then if I type "quit" to get the prompt back, the window 
> > persists as required, but grid button no longer works.
> 
> You are trying to use "persist" for something beyond what
> it was intended for.

I was mainly surprised that qt didn't behave like wxt. But this is
partly due to incomplete documentation (partly solved, but the man
page should be updated too) and poor UI: when a feature provided by
a button is not available, the button is normally greyed out; this is
not the case here. Alternatively, an error message could be displayed
when a non-working button ("show grid" or zoom) is clicked.

> Now it is true that some terminal types are smart enough
> to toggle the grid on/off even in persistent mode after
> the main program has exiting.   It would be possible to
> make qt do that also, but only if the original plot already
> contained a grid.  And that is only possible because it 
> isn't really necessary to regenerate the whole plot just
> to make the grid lines [in]visible.  It doesn't change
> the basic limitation.    If toggling the grid is important
> to you by itself, could you please file a feature request
> for uniform support to toggle it off in terminals that
> support a persistent mode?   It would be easy in qt, but
> I'd have to think about the other terminals.

Well, toggling the grid and zooming may be important in some cases.
When gnuplot is used in a script, there should be a way to use these
features (I'm not saying to use "persist", it could be something
like "pause mouse keypress" + some other code but it seems to badly
interact with the buttons) and make the gnuplot processes terminate
when the terminal is closed by the user ('q', 'Ctrl-q', via the
window manager, or whatever). See

  https://sourceforge.net/p/gnuplot/bugs/1418/#645d

and my reply.

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Vincent Lefèvre <vincent at vinc17.net> - Web: <https://www.vinc17.net/>
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