[vte] build: Bump gtk min-req version to 3.18

[Egmont Koblinger <egmontkob src gnome org>]

commit 9102b9d8ae547bfda9e8d336139b3ed6450b6d2c
Author: Egmont Koblinger <egmont gmail com>
Date:   Wed Sep 18 14:16:41 2019 +0200

    build: Bump gtk min-req version to 3.18
    
    https://gitlab.gnome.org/GNOME/vte/issues/172

 meson.build    | 2 +-
 src/app/app.cc | 5 ++++-
 src/reflect.c  | 5 +++--
 3 files changed, 8 insertions(+), 4 deletions(-)
---
diff --git a/meson.build b/meson.build
index bb2bba21..6caea373 100644
--- a/meson.build
+++ b/meson.build
@@ -32,7 +32,7 @@ project(
 # Requirements
 
 gtk3_req_version          = '3.20.0'
-gtk3_min_req_version      = '3.6'
+gtk3_min_req_version      = '3.18'
 gtk3_max_allowed_version  = '3.20'
 gtk4_req_version          = '4.0.0'
 
diff --git a/src/app/app.cc b/src/app/app.cc
index d7ed9b04..5e9f852f 100644
--- a/src/app/app.cc
+++ b/src/app/app.cc
@@ -1902,8 +1902,11 @@ vteapp_window_constructed(GObject *object)
                 g_signal_connect(window->terminal, "notify", G_CALLBACK(window_notify_cb), window);
 
         /* Settings */
-        if (options.no_double_buffer)
+        if (options.no_double_buffer) {
+                G_GNUC_BEGIN_IGNORE_DEPRECATIONS;
                 gtk_widget_set_double_buffered(GTK_WIDGET(window->terminal), false);
+                G_GNUC_END_IGNORE_DEPRECATIONS;
+        }
 
         if (options.encoding != nullptr) {
                 GError* err = nullptr;
diff --git a/src/reflect.c b/src/reflect.c
index beb658c5..63d47da3 100644
--- a/src/reflect.c
+++ b/src/reflect.c
@@ -274,10 +274,11 @@ main(int argc, char **argv)
 
        label = gtk_label_new("");
        gtk_label_set_justify(GTK_LABEL(label), GTK_JUSTIFY_LEFT);
-       gtk_misc_set_alignment(GTK_MISC(label), 0, 0);
+        gtk_label_set_xalign(GTK_LABEL(label), 0.0);
+        gtk_label_set_yalign(GTK_LABEL(label), 0.0);
 
        sw = gtk_scrolled_window_new(NULL, NULL);
-       gtk_scrolled_window_add_with_viewport(GTK_SCROLLED_WINDOW(sw), label);
+        gtk_container_add(GTK_CONTAINER(sw), label);
        gtk_widget_show(label);
 
        pane = gtk_paned_new (GTK_ORIENTATION_VERTICAL);