[gtk/overlay-scrolling-setting: 1/2] Add a gtk-overlay-scrolling setting

[Matthias Clasen <matthiasc src gnome org>]

commit f6a8c851d61b47e48d8c9cb97de2295425444436
Author: Matthias Clasen <mclasen redhat com>
Date:   Wed May 22 19:24:24 2019 +0000

    Add a gtk-overlay-scrolling setting
    
    This is in preparation for letting user opt out of
    overlay scrolling in the control-center.

 gdk/wayland/gdkdisplay-wayland.c |  3 ++-
 gdk/x11/gdksettings.c            |  1 +
 gtk/gtksettings.c                | 19 ++++++++++++++++++-
 3 files changed, 21 insertions(+), 2 deletions(-)
---
diff --git a/gdk/wayland/gdkdisplay-wayland.c b/gdk/wayland/gdkdisplay-wayland.c
index d721026d54..23c64b6f26 100644
--- a/gdk/wayland/gdkdisplay-wayland.c
+++ b/gdk/wayland/gdkdisplay-wayland.c
@@ -1628,6 +1628,7 @@ static TranslationEntry translations[] = {
   { FALSE, "org.gnome.desktop.interface", "gtk-im-module", "gtk-im-module", G_TYPE_STRING, { .s = "simple" } 
},
   { FALSE, "org.gnome.desktop.interface", "enable-animations", "gtk-enable-animations", G_TYPE_BOOLEAN, { .b 
= TRUE } },
   { FALSE, "org.gnome.desktop.interface", "gtk-enable-primary-paste", "gtk-enable-primary-paste", 
G_TYPE_BOOLEAN, { .b = TRUE } },
+  { FALSE, "org.gnome.desktop.interface", "overlay-scrolling", "gtk-overlay-scrolling", G_TYPE_BOOLEAN, { .b 
= TRUE } },
   { FALSE, "org.gnome.settings-daemon.peripherals.mouse", "double-click", "gtk-double-click-time", 
G_TYPE_INT, { .i = 400 } },
   { FALSE, "org.gnome.settings-daemon.peripherals.mouse", "drag-threshold", "gtk-dnd-drag-threshold", 
G_TYPE_INT, {.i = 8 } },
   { FALSE, "org.gnome.desktop.sound", "theme-name", "gtk-sound-theme-name", G_TYPE_STRING, { .s = 
"freedesktop" } },
@@ -1645,7 +1646,7 @@ static TranslationEntry translations[] = {
   { FALSE, "org.gnome.desktop.wm.preferences", "action-middle-click-titlebar", "gtk-titlebar-middle-click", 
G_TYPE_STRING, { .s = "none" } },
   { FALSE, "org.gnome.desktop.wm.preferences", "action-right-click-titlebar", "gtk-titlebar-right-click", 
G_TYPE_STRING, { .s = "menu" } },
   { FALSE, "org.gnome.desktop.a11y", "always-show-text-caret", "gtk-keynav-use-caret", G_TYPE_BOOLEAN, { .b 
= FALSE } },
-  { FALSE, "org.gnome.fontconfig", "serial", "gtk-fontconfig-timestamp", G_TYPE_NONE, { .i = 0 } }
+  { FALSE, "org.gnome.fontconfig", "serial", "gtk-fontconfig-timestamp", G_TYPE_NONE, { .i = 0 } },
 };
 
 
diff --git a/gdk/x11/gdksettings.c b/gdk/x11/gdksettings.c
index c07df4c05e..3fe596f49e 100644
--- a/gdk/x11/gdksettings.c
+++ b/gdk/x11/gdksettings.c
@@ -66,6 +66,7 @@ static const struct {
   {"Gtk/RecentFilesMaxAge",   "gtk-recent-files-max-age"},
   {"Gtk/RecentFilesEnabled",  "gtk-recent-files-enabled"},
   {"Gtk/KeynavUseCaret",      "gtk-keynav-use-caret"},
+  {"Gtk/OverlayScrolling",    "gtk-overlay-scrolling"},
 
   /* These are here in order to be recognized, but are not sent to
      gtk as they are handled internally by gdk: */
diff --git a/gtk/gtksettings.c b/gtk/gtksettings.c
index 18c3fd4eb0..77aeb3bf1b 100644
--- a/gtk/gtksettings.c
+++ b/gtk/gtksettings.c
@@ -191,7 +191,8 @@ enum {
   PROP_ENABLE_PRIMARY_PASTE,
   PROP_RECENT_FILES_ENABLED,
   PROP_LONG_PRESS_TIME,
-  PROP_KEYNAV_USE_CARET
+  PROP_KEYNAV_USE_CARET,
+  PROP_OVERLAY_SCROLLING
 };
 
 /* --- prototypes --- */
@@ -1002,6 +1003,22 @@ gtk_settings_class_init (GtkSettingsClass *class)
                                                                    GTK_PARAM_READWRITE),
                                              NULL);
   g_assert (result == PROP_KEYNAV_USE_CARET);
+
+  /**
+   * GtkSettings:gtk-overlay-scrolling:
+   *
+   * Whether scrolled windows may use overlayed scrolling indicators.
+   * If this is set to %FALSE, scrolled windows will have permanent
+   * scrollbars.
+   */
+  result = settings_install_property_parser (class,
+                                             g_param_spec_boolean ("gtk-overlay-scrolling",
+                                                                   P_("Whether to use overlay scrollbars"),
+                                                                   P_("Whether to use overlay scrollbars"),
+                                                                   TRUE,
+                                                                   GTK_PARAM_READWRITE),
+                                             NULL);
+  g_assert (result == PROP_OVERLAY_SCROLLING);
 }
 
 static GtkSettings *