Also, you should only use Layout attached properties when the object you’re using it on is a child of a Layout, for example:
<span style="color:#323232;">ApplicationWindow {
</span><span style="color:#323232;"> ColumnLayout {
</span><span style="color:#323232;"> anchors.fill: parent // Not a child of a layout, so you use anchors
</span><span style="color:#323232;"> Controls.Button {
</span><span style="color:#323232;"> Layout.fillWidth: true // It's a child of a layout, so you use Layout.fillWidth
</span><span style="color:#323232;"> }
</span><span style="color:#323232;"> }
</span><span style="color:#323232;">}
</span>