Main: Store window geomety with KConfig.WindowStateSaver

src/contents/ui/main.qml

@@ -9,6 +9,7 @@ import org.kde.kirigami as Kirigami
 import QtMultimedia
 
 import org.kde.ytmusic 1.0
+import org.kde.config as KConfig
 
 import org.nemomobile.qtmpris 1.0
 
@@ -30,6 +31,10 @@ Kirigami.ApplicationWindow {
     property bool wideScreen: width >= 600
     property bool showSearch: false // only applicable if not widescreen
 
+    KConfig.WindowStateSaver {
+        configGroupName: "Window"
+    }
+
     // so that there is still a separator, since the header style is none
     Kirigami.Separator {
         anchors.top: parent.top