Bug#831369: audacity: In LADSPA effect settings, sliders cannot handle negative integers

[Kyanos]

Package: audacity
Version: 2.1.2-1+b1
Severity: minor

Dear Maintainer,

In the settings window for LADSPA effects, the sliders do not move to
negative integers. If, for example, an integer option ranges from -3 to
3 (inclusive), the slider will only move within one half of the bar.

What is interesting is that negative values can still be entered
manually, and the slider will even move to the appropriate position in
the negative part! But trying to adjust the slider will cause it to jump
back to the 0 position.

Also, the lower-bound label for the slider is incorrect when negative
integers are involved: It is one greater than the true lower bound. So,
if the range were from -3 to 3, the lower-bound label would be -2.
However, the slider seems to behave as if the lower bound is correct.

I first discovered these issues while using Tom Baran's Autotalent
plugin (packaged as "autotalent"), so that may be used to reproduce
these issues. I have also attached a test plugin which may help.

Thank you for your consideration.

Kyanos

-- System Information:
Debian Release: stretch/sid
  APT prefers testing
  APT policy: (500, 'testing'), (300, 'oldstable-updates'), (300,
'oldstable')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 4.6.0-1-amd64 (SMP w/4 CPU cores)
Locale: LANG=en_US.utf8, LC_CTYPE=en_US.utf8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

Versions of packages audacity depends on:
ii  audacity-data       2.1.2-1
ii  libasound2          1.1.1-2
ii  libavcodec57        7:3.0.2-4
ii  libavformat57       7:3.0.2-4
ii  libavutil55         7:3.0.2-4
ii  libc6               2.23-1
ii  libexpat1           2.2.0-1
ii  libflac++6v5        1.3.1-4
ii  libflac8            1.3.1-4
ii  libgcc1             1:6.1.1-9
ii  libgdk-pixbuf2.0-0  2.34.0-1
ii  libglib2.0-0        2.48.1-1
ii  libgtk2.0-0         2.24.30-2
ii  libid3tag0          0.15.1b-11
ii  liblilv-0-0         0.22.0~dfsg0-1
ii  libmad0             0.15.1b-8
ii  libmp3lame0         3.99.5+repack1-9+b1
ii  libogg0             1.3.2-1
ii  libportaudio2       19+svn20140130-1
ii  libportsmf0         0.1~svn20101010-4
ii  libsbsms10          2.0.2-1
ii  libsndfile1         1.0.25-10
ii  libsoundtouch1      1.9.2-2
ii  libsoxr0            0.1.2-1
ii  libstdc++6          6.1.1-9
ii  libsuil-0-0         0.8.2~dfsg0-1
ii  libtwolame0         0.3.13-1.2
ii  libvamp-hostsdk3v5  2.6~repack0-2
ii  libvorbis0a         1.3.5-3
ii  libvorbisenc2       1.3.5-3
ii  libvorbisfile3      1.3.5-3
ii  libwxbase3.0-0v5    3.0.2+dfsg-1.4
ii  libwxgtk3.0-0v5     3.0.2+dfsg-1.4

audacity recommends no packages.

Versions of packages audacity suggests:
ii  autotalent [ladspa-plugin]   0.2-5
ii  caps [ladspa-plugin]         0.9.24-2
ii  ladspa-sdk [ladspa-plugin]   1.13-2+b1
ii  swh-plugins [ladspa-plugin]  0.4.16+git20160602~repack1-2
ii  tap-plugins [ladspa-plugin]  0.7.3-1

-- no debconf information
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