Bug#911462: libgtk-3-0: Filefilter Combobox shows much too much whitespace with long lists or on bottom of screen

[Richard Duivenvoorde]

Package: libgtk-3-0
Version: 3.24.1-2
Severity: normal

Dear Maintainer,

In QGIS we have in some filechooser applications long lists of filetypes.
One of them (for a screenshot see https://issues.qgis.org/issues/20169)·
shows a very long piece of whitespace above the filetypes in the combobox.
First I thought it was a QGIS problem.

But after some fiddling I was able to reproduce this with almost all comboboxes
in Gnome applications, by moving the combobox (with for example "All Files" etc)
all to the bottom of you screens. Then open the list and see that it looks
like the canvas to be used to draw the items on is first created ON screen,
then the items are painted on it, and then the last selection is selected.
Sometimes showing little arrows/pointers to scroll up or down.
But sometimes the whitespace above the first item sticks.
And sometimes the canvas does not move down.
In our (QGIS) case this give alwasy rise to a huge unused part of whitespace
above the first item.

I think this is an upstream issue, as I can reproduce it with all Gnome
apps, but maybe not.


-- System Information:
Debian Release: buster/sid
  APT prefers testing
  APT policy: (500, 'testing')
Architecture: amd64 (x86_64)

Kernel: Linux 4.18.0-2-amd64 (SMP w/8 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages libgtk-3-0 depends on:
ii  adwaita-icon-theme   3.30.0-1
ii  hicolor-icon-theme   0.17-2
ii  libatk-bridge2.0-0   2.30.0-2
ii  libatk1.0-0          2.30.0-1
ii  libc6                2.27-6
ii  libcairo-gobject2    1.15.12-1
ii  libcairo2            1.15.12-1
ii  libcolord2           1.3.3-2
ii  libcups2             2.2.8-5
ii  libepoxy0            1.5.3-0.1
ii  libfontconfig1       2.13.1-1
ii  libfreetype6         2.8.1-2
ii  libgdk-pixbuf2.0-0   2.38.0+dfsg-6
ii  libglib2.0-0         2.58.1-2
ii  libgtk-3-common      3.24.1-2
ii  libharfbuzz0b        1.9.0-1
ii  libjson-glib-1.0-0   1.4.4-1
ii  libpango-1.0-0       1.42.4-3
ii  libpangocairo-1.0-0  1.42.4-3
ii  libpangoft2-1.0-0    1.42.4-3
ii  librest-0.7-0        0.8.0-2
ii  libsoup2.4-1         2.64.1-3
ii  libwayland-client0   1.16.0-1
ii  libwayland-cursor0   1.16.0-1
ii  libwayland-egl1      1.16.0-1
ii  libx11-6             2:1.6.7-1
ii  libxcomposite1       1:0.4.4-2
ii  libxcursor1          1:1.1.15-1
ii  libxdamage1          1:1.1.4-3
ii  libxext6             2:1.3.3-1+b2
ii  libxfixes3           1:5.0.3-1
ii  libxi6               2:1.7.9-1
ii  libxinerama1         2:1.1.4-1
ii  libxkbcommon0        0.8.2-1
ii  libxml2              2.9.4+dfsg1-7+b1
ii  libxrandr2           2:1.5.1-1
ii  shared-mime-info     1.10-1

Versions of packages libgtk-3-0 recommends:
ii  libgtk-3-bin  3.24.1-2

Versions of packages libgtk-3-0 suggests:
ii  gvfs             1.38.0-2
ii  librsvg2-common  2.40.20-3

Versions of packages libgtk-3-0 is related to:
pn  appmenu-gtk3-module                    <none>
ii  fcitx-frontend-gtk3                    1:4.2.9.6-5
pn  gcin-gtk3-immodule                     <none>
pn  gtk-vector-screenshot                  <none>
pn  gtk3-engines-xfce                      <none>
ii  gtk3-im-libthai                        0.2.1-8
pn  hime-gtk3-immodule                     <none>
ii  ibus-gtk3                              1.5.19-1
pn  imhangul-gtk3                          <none>
ii  libcanberra-gtk3-module                0.30-6
pn  libcaribou-gtk3-module                 <none>
pn  libgtk3-nocsd0                         <none>
pn  maliit-inputcontext-gtk3               <none>
pn  packagekit-gtk3-module                 <none>
ii  scim-gtk-immodule [scim-gtk-immodule]  1.4.18-2.1
pn  topmenu-gtk3                           <none>
ii  uim-gtk3                               1:1.8.8-3
ii  uim-gtk3-immodule                      1:1.8.8-3

-- no debconf information