[gnome-games] display-header-bar: Add transition

[Alexander Mikhaylenko <alexm src gnome org>]

commit 2920d81a954645db6f6e67050c0691d2d31eb30d
Author: Alexander Mikhaylenko <exalm7659 gmail com>
Date:   Mon Aug 19 21:32:59 2019 +0500

    display-header-bar: Add transition
    
    Adjust duration to 250ms to match the revealer.

 data/ui/display-header-bar.ui | 2 ++
 1 file changed, 2 insertions(+)
---
diff --git a/data/ui/display-header-bar.ui b/data/ui/display-header-bar.ui
index 8a659bd8..339e941c 100644
--- a/data/ui/display-header-bar.ui
+++ b/data/ui/display-header-bar.ui
@@ -8,6 +8,8 @@
     <child>
       <object class="GtkStack" id="stack">
         <property name="visible">True</property>
+        <property name="transition-type">crossfade</property>
+        <property name="transition-duration">250</property>
         <child>
           <object class="GtkHeaderBar" id="ingame_header_bar">
             <property name="visible">True</property>