ui: listen for GDK_SMOOTH_SCROLL events

On Wayland, without grabbing focus, two-finger scrolling generates
GDK_SMOOTH_SCROLL events instead of GDK_SCROLL_*, so listen for them.

Signed-off-by: Sergio Lopez <slp@redhat.com>
Message-id: 20190204120823.41333-1-slp@redhat.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

ui/gtk.c

@@ -2045,6 +2045,7 @@ static GSList *gd_vc_gfx_init(GtkDisplayState *s, VirtualConsole *vc,
                           GDK_ENTER_NOTIFY_MASK |
                           GDK_LEAVE_NOTIFY_MASK |
                           GDK_SCROLL_MASK |
+                          GDK_SMOOTH_SCROLL_MASK |
                           GDK_KEY_PRESS_MASK);
     gtk_widget_set_can_focus(vc->gfx.drawing_area, TRUE);