diff --git a/build-relocatable-install.py b/build-relocatable-install.py
index 2e016b04e6a842fa060618cbe896af97cd45b861..42f82b99f5e6441361dd31d0e154ab2a4f7284ca 100755
--- a/build-relocatable-install.py
+++ b/build-relocatable-install.py
@@ -91,6 +91,7 @@ PRIMARY_ARCH_DEPENDENCIES = {
     'libselinux1': 'libselinux',
 }
 SCRIPTS = [
+    'pressure-vessel-test-ui',
     'pressure-vessel-unruntime',
     'pressure-vessel-wrap'
 ]
diff --git a/meson.build b/meson.build
index 67b6264768d7ea10cba0ebfc9e02986d0251e6f1..8b1a24ca653e7a076d5374c190b756ce4fe01310 100644
--- a/meson.build
+++ b/meson.build
@@ -40,6 +40,7 @@ endif
 
 scripts = [
   'pressure-vessel-wrap',
+  'pressure-vessel-test-ui',
   'pressure-vessel-unruntime',
 ]
 
diff --git a/pressure-vessel-test-ui b/pressure-vessel-test-ui
new file mode 100755
index 0000000000000000000000000000000000000000..f86b4dd043ef48913676bafc3d207c90916e56eb
--- /dev/null
+++ b/pressure-vessel-test-ui
@@ -0,0 +1,166 @@
+#!/usr/bin/env python3
+
+# Copyright © 2019 Collabora Ltd.
+#
+# SPDX-License-Identifier: MIT
+#
+# Permission is hereby granted, free of charge, to any person obtaining
+# a copy of this software and associated documentation files (the
+# "Software"), to deal in the Software without restriction, including
+# without limitation the rights to use, copy, modify, merge, publish,
+# distribute, sublicense, and/or sell copies of the Software, and to
+# permit persons to whom the Software is furnished to do so, subject to
+# the following conditions:
+#
+# The above copyright notice and this permission notice shall be included
+# in all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+# IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+# CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+# TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+# SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+import logging
+import os
+import sys
+
+try:
+    import typing
+except ImportError:
+    pass
+else:
+    typing      # silence pyflakes
+
+import gi
+gi.require_version('Gtk', '3.0')
+
+from gi.repository import Gtk
+
+logger = logging.getLogger('pressure-vessel-test-ui')
+
+
+class Gui:
+    def __init__(self):
+        self.window = Gtk.Window()
+        self.window.set_default_size(600, 300)
+        self.window.connect('delete-event', Gtk.main_quit)
+        self.window.set_title('Choose pressure-vessel runtime')
+
+        self.grid = Gtk.Grid(
+            row_spacing=6,
+            column_spacing=6,
+            margin_top=12,
+            margin_bottom=12,
+            margin_start=12,
+            margin_end=12,
+        )
+        self.window.add(self.grid)
+
+        row = 0
+
+        runtime_label = Gtk.Label.new('Runtime')
+        self.grid.attach(runtime_label, 0, row, 1, 1)
+
+        self.runtime_combo = Gtk.ComboBoxText.new()
+        self.runtime_combo.append('/', 'None (use host system)')
+        self.runtime_combo.append('scout', "SteamRT 1 'scout' (./scout)")
+        self.runtime_combo.append('spy', "SteamRT 2 'spy' (./spy)")
+        self.runtime_combo.set_active(1)
+        self.grid.attach(self.runtime_combo, 1, row, 1, 1)
+
+        row += 1
+
+        self.native_check = Gtk.CheckButton.new_with_label(
+            'Use native-code version of pressure-vessel-wrap'
+        )
+        self.grid.attach(self.native_check, 1, row, 1, 1)
+
+        row += 1
+
+        self.share_home_check = Gtk.CheckButton.new_with_label(
+            'Share real home directory'
+        )
+        self.share_home_check.set_active(True)
+        self.grid.attach(self.share_home_check, 1, row, 1, 1)
+
+        row += 1
+
+        self.xterm_check = Gtk.CheckButton.new_with_label('Run in an xterm')
+        self.xterm_check.set_active(True)
+        self.grid.attach(self.xterm_check, 1, row, 1, 1)
+
+        row += 1
+
+        buttons_grid = Gtk.Grid(
+            column_spacing=6,
+            column_homogeneous=True,
+            halign=Gtk.Align.END,
+        )
+
+        cancel_button = Gtk.Button.new_with_label('Cancel')
+        cancel_button.connect('clicked', Gtk.main_quit)
+        buttons_grid.attach(cancel_button, 0, 0, 1, 1)
+
+        run_button = Gtk.Button.new_with_label('Run')
+        run_button.connect('clicked', self.run_cb)
+        buttons_grid.attach(run_button, 1, 0, 1, 1)
+
+        self.grid.attach(buttons_grid, 0, row, 2, 1)
+
+        row += 1
+
+    def run_cb(self, _ignored=None):
+
+        if self.native_check.get_active():
+            wrap = 'pressure-vessel-wrap-c'
+        else:
+            wrap = 'pressure-vessel-wrap'
+
+        argv = [
+            'env',
+            'G_MESSAGES_DEBUG=all',
+            os.path.join(
+                os.path.dirname(sys.argv[0]),
+                wrap,
+            ),
+        ]
+
+        id = self.runtime_combo.get_active_id()
+
+        if id is None:
+            pass
+        elif id == '/':
+            pass
+        else:
+            path = os.path.join(
+                os.path.dirname(sys.argv[0]),
+                '..',
+                id,
+                'files',
+            )
+            argv.append('--runtime')
+            argv.append(path)
+
+        if self.share_home_check.get_active():
+            argv.append('--share-home')
+        else:
+            argv.append('--unshare-home')
+
+        if self.xterm_check.get_active():
+            argv.append('--xterm')
+
+        argv.append('--verbose')
+        argv.extend(sys.argv[1:])
+
+        os.execvp(argv[0], argv)
+
+    def run(self):
+        self.window.show_all()
+        Gtk.main()
+
+
+if __name__ == '__main__':
+    Gui().run()
diff --git a/pressure-vessel-unruntime b/pressure-vessel-unruntime
index f5df1d718c9beb07dffb765a7d5472041a15954b..4c3556d45351e2b8134f456580424b1226858783 100755
--- a/pressure-vessel-unruntime
+++ b/pressure-vessel-unruntime
@@ -96,6 +96,10 @@ for word in $ld_preload; do
 done
 IFS="$old_IFS"
 
+if [ -n "${PRESSURE_VESSEL_WRAP_GUI+set}" ]; then
+    exec "${here}/pressure-vessel-test-ui" ${options+"${options[@]}"} "$@"
+fi
+
 if [ -n "${PRESSURE_VESSEL_WRAP_NATIVE+set}" ]; then
     exec "${here}/pressure-vessel-wrap-c" ${options+"${options[@]}"} "$@"
 fi
diff --git a/t/mypy.sh b/t/mypy.sh
index 3d0d9c44d2b38687bf2e415aa9a7596e27cec1bb..b552359755e1ef2deba9ab26d067d523c7cb0a24 100755
--- a/t/mypy.sh
+++ b/t/mypy.sh
@@ -21,6 +21,7 @@ export MYPYPATH="${PYTHONPATH:="$(pwd)"}"
 i=0
 for script in \
     "${G_TEST_SRCDIR}"/*.py \
+    "${G_TEST_SRCDIR}"/pressure-vessel-test-ui \
     "${G_TEST_SRCDIR}"/sysroot/*.py \
 ; do
     i=$((i + 1))
diff --git a/t/pycodestyle.sh b/t/pycodestyle.sh
index f3481eddba5445dfec04b0fe66f3bf79dcee2386..0c0113a1b8bcda8b52d895c2f8d41afca1a05c0f 100755
--- a/t/pycodestyle.sh
+++ b/t/pycodestyle.sh
@@ -24,8 +24,13 @@ fi
 
 echo "1..1"
 
+# Ignore E402: when using GObject-Introspection, not all imports
+# can come first
+
 if "${PYCODESTYLE}" \
+    --ignore=E402 \
     "$G_TEST_SRCDIR"/*.py \
+    "${G_TEST_SRCDIR}"/pressure-vessel-test-ui \
     "${G_TEST_SRCDIR}"/sysroot/*.py \
     >&2; then
     echo "ok 1 - $PYCODESTYLE reported no issues"
diff --git a/t/pyflakes.sh b/t/pyflakes.sh
index db2c87e91f7c938e40434f2f4707a156acbbcce8..5134e76448382cd6dc807a3198a976cc062a7f32 100755
--- a/t/pyflakes.sh
+++ b/t/pyflakes.sh
@@ -21,6 +21,7 @@ if [ "x${PYFLAKES:=pyflakes3}" = xfalse ] || \
     echo "1..0 # SKIP pyflakes3 not found"
 elif "${PYFLAKES}" \
     "${G_TEST_SRCDIR}"/*.py \
+    "${G_TEST_SRCDIR}"/pressure-vessel-test-ui \
     "${G_TEST_SRCDIR}"/sysroot/*.py \
     >&2; then
     echo "1..1"