Most Guix system setup with desktop evironment will install GDK_PIXBUF_MODULE_FILE
environment variable in the system profile, and it'll be leaked into the sandbox
environment of flatpak, so the applications in sandbox may fail to find correct
GdkPixbuf loaders.

This patch unset the GDK_PIXBUF_MODULE_FILE environment variable before running
the sandboxed applications, prevents it to load GdkPixbuf loaders from the path
of host system.

--- a/common/flatpak-run.c
+++ b/common/flatpak-run.c
@@ -1900,6 +1900,7 @@ static const ExportData default_exports[] = {
   {"XKB_CONFIG_ROOT", NULL},
   {"GIO_EXTRA_MODULES", NULL},
   {"GDK_BACKEND", NULL},
+  {"GDK_PIXBUF_MODULE_FILE", NULL},
   {"VK_ADD_DRIVER_FILES", NULL},
   {"VK_ADD_LAYER_PATH", NULL},
   {"VK_DRIVER_FILES", NULL},
ipts'>koszko-scripts</option>
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<div class='path'>path: <a href='/guix/log/?id=b95fbb510db87576d9a54e4264618b6f6f259b05'>root</a>/<a href='/guix/log/gnu?id=b95fbb510db87576d9a54e4264618b6f6f259b05'>gnu</a>/<a href='/guix/log/gnu/installer?id=b95fbb510db87576d9a54e4264618b6f6f259b05'>installer</a>/<a href='/guix/log/gnu/installer/newt.scm?id=b95fbb510db87576d9a54e4264618b6f6f259b05'>newt.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/gnu/installer/newt.scm?id=b95fbb510db87576d9a54e4264618b6f6f259b05&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2020-12-11 21:37:07 +0100'>2020-12-11</span></td><td><a href='/guix/commit/gnu/installer/newt.scm?id=8361817bf693742757b096468198626f297bb09e'>install: Discover local substitute servers.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/installer/substitutes.scm: New file.
* gnu/installer/newt/substitutes.scm: New file.
* gnu/local.mk (INSTALLER_MODULES): Add them.
* po/guix/POTFILES.in: Add gnu/installer/newt/substitutes.scm.
* gnu/installer/proxy.scm (with-silent-shepherd): Move to ...
* gnu/installer/utils.scm: ... here.
* gnu/installer/record.scm (&lt;installer&gt;)[substitutes-page]: New field.
* gnu/installer/newt.scm (substitutes-page): New procedure,
(newt-installer): register it.
* gnu/installer.scm (installer-steps): Add "substitutes-page" step.
* gnu/system/install.scm (%installation-services): Add avahi-service-type and
enable substitute server discover in guix-service-type.
[&lt;name-service-switch&gt;]: Set it to %mdns-host-lookup-nss.
</span></span></td><td>Mathieu Othacehe</td></tr>
<tr><td><span title='2020-11-07 13:19:25 +0100'>2020-11-07</span></td><td><a href='/guix/commit/gnu/installer/newt.scm?id=8338d414b361e4fb961221642c1064e9dc89ba65'>installer: Limit listbox height.</a><span class='msg-avail'>...<span class='msg-tooltip'>Fixes: &lt;https://issues.guix.gnu.org/44428&gt;.

* gnu/installer/newt.scm (init): Print screen size.
* gnu/installer/newt/page.scm (default-listbox-height): New variable.
(run-listbox-selection-page): Use it.
* gnu/installer/newt/wifi.scm (wifi-listbox-height): Ditto.
* gnu/installer/newt/network.scm (run-technology-page): Set the maximum
listbox height to 5.
* gnu/installer/newt/ethernet.scm (run-ethernet-page): Ditto.
* gnu/installer/newt/final.scm (run-config-display-page): Change listbox
height.
* gnu/installer/newt/partition.scm (run-disk-page): Ditto.
* gnu/installer/newt/welcome.scm (display-logo?): New procedure.
(run-menu-page): Use it.
* gnu/installer/steps.scm (%configuration-file-width): Remove it.
</span></span></td><td>Mathieu Othacehe</td></tr>
<tr><td><span title='2020-09-21 00:31:15 +0200'>2020-09-21</span></td><td><a href='/guix/commit/gnu/installer/newt.scm?id=5e17ae7fbd38917264627701b73e7f38061402f0'>installer: Rename RUN-PARTIONING-PAGE.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/installer/newt/partition.scm (run-partioning-page): Rename to
run-partitioning-page.  Adjust all callers.
</span></span></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2020-04-08 10:24:02 +0200'>2020-04-08</span></td><td><a href='/guix/commit/gnu/installer/newt.scm?id=07a53bd512530d8f87e076263227216c467727bb'>installer: Turn help menu into parameters menu.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/local.mk (INSTALLER_MODULES): Rename help.scm into parameters.scm.
* po/guix/POTFILES.in: Ditto.
* gnu/installer/record.scm (&lt;installer&gt;): Rename help-menu into parameter-menu
and help-page into parameters-page.
* gnu/installer/newt/parameters.scm: Renamed from help.scm. Update information
messages.
* gnu/installer/newt.scm: Update accordingly.
* gnu/installer/newt/keymap.scm: Ditto.
</span></span></td><td>Mathieu Othacehe</td></tr>
<tr><td><span title='2020-04-06 15:06:03 +0200'>2020-04-06</span></td><td><a href='/guix/commit/gnu/installer/newt.scm?id=786c9c39bc0826737e99f0c750ea30033cdbc202'>installer: Add a help page.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/installer/newt/help.scm: New file.
* gnu/local.mk (INSTALLER_MODULES): Add it.
* po/guix/POTFILES.in: Add it.
* gnu/installer/record.scm (&lt;installer&gt;): Add 'help-menu' and 'help-page'
 fields,
 (installer-help-menu, installer-help-page): new exported procedures.
 * gnu/installer/newt.scm (init): Set the help line,
 (help-menu, help-page): new procedures used ...
 (newt-installer): ... here.
 * gnu/installer/newt/keymap.scm (run-layout-page): Add a context argument to
 differenciate the help context from the main one,
 (run-keymap-page): add a context argument and pass it to run-layout-page.
 * gnu/installer.scm (compute-keymap-step): Add a context argument and pass it
 to 'installer-keymap-page',
 (installer-steps): set the help menu and pass the appropriate context to
 compute-keymap-step calls,
 (guile-newt): update to revision 2.
</span></span></td><td>Mathieu Othacehe</td></tr>