Bug#711142: gnuplot-qt: zooming with the 'qt' and 'wxt' terminals yields blank contents

[Vincent Lefevre]

Control: reopen -1
Control: retitle -1 zooming yields blank contents when there should be a part of a segment
Control: found -1 4.6.5-4

On 2014-06-11 14:44:08 +0200, Vincent Lefevre wrote:
> Actually the problem with the 'qt' terminal is due to the -persist;
> this is discussed in bug 711139.

After some other tests, I also get blank contents without -persist,
but this bug seems to occur only when the result should be a part of
a segment. I've tried the latest version (4.6.5-4) with 'qt' (default)
and 'x11' only, as 'wxt' is no longer available.

A test without -persist:

xvii:~> GNUTERM=qt gnuplot

        G N U P L O T
        Version 4.6 patchlevel 5    last modified February 2014
        Build System: Linux x86_64

        Copyright (C) 1986-1993, 1998, 2004, 2007-2014
        Thomas Williams, Colin Kelley and many others

        gnuplot home:     http://www.gnuplot.info
        faq, bugs, etc:   type "help FAQ"
        immediate help:   type "help"  (plot window: hit 'h')

Terminal type set to 'qt'
gnuplot> plot '-' using 1:2 t '' with line
input data ('e' ends) > 0 0
input data ('e' ends) > 3 3
input data ('e' ends) > 6 8
input data ('e' ends) > e
gnuplot> 

Then select any area that contains a part of a single segment
(e.g. (1,2) to (2,1), or (4,7) to (5,1)) with the right button.
I get a blank graph (only the axes). However if I select any
area that contains (3,3), I get the correct result.

-- 
Vincent Lefèvre <vincent at vinc17.net> - Web: <https://www.vinc17.net/>
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Work: CR INRIA - computer arithmetic / AriC project (LIP, ENS-Lyon)