[shotwell/shotwell-0.30] Also set dark wallpaper uri

[Jens Georg <jensgeorg src gnome org>]

commit cfd4249398b16e1c36891e6265fd8d95783e2cb9
Author: Jens Georg <mail jensge org>
Date:   Mon Apr 4 21:58:55 2022 +0200

    Also set dark wallpaper uri
    
    Work-around non-working wallpaper in dark mode
    
    Fixes lp#1965812

 src/config/GSettingsEngine.vala | 3 +++
 1 file changed, 3 insertions(+)
---
diff --git a/src/config/GSettingsEngine.vala b/src/config/GSettingsEngine.vala
index a3d4e04e..f8f2ef08 100644
--- a/src/config/GSettingsEngine.vala
+++ b/src/config/GSettingsEngine.vala
@@ -357,6 +357,9 @@ public class GSettingsConfigurationEngine : ConfigurationEngine, GLib.Object {
             converted_val = "file://" + val;
         }
 
+        if (p == ConfigurableProperty.DESKTOP_BACKGROUND_FILE) {
+            set_gs_string(schema_names[p], key_names[p] + "-dark", converted_val);
+        }
         set_gs_string(schema_names[p], key_names[p], converted_val);
         property_changed(p);
     }