diff --git a/kcmkwin/kwindecoration/package/contents/ui/main.qml b/kcmkwin/kwindecoration/package/contents/ui/main.qml
--- a/kcmkwin/kwindecoration/package/contents/ui/main.qml
+++ b/kcmkwin/kwindecoration/package/contents/ui/main.qml
@@ -39,6 +39,9 @@
     rightPadding: leftPadding
     bottomPadding: leftPadding
 
+    implicitWidth: tabLayout.implicitWidth
+    implicitHeight: tabLayout.implicitHeight
+
     ColumnLayout {
         id: tabLayout
         anchors.fill: parent