states: State {
            name: "visible"
            when: inputPanel.active
            PropertyChanges {
                target: inputPanel
                y: window.height - inputPanel.height
            }
        }

Warning: /home/luchen/Documents/QtProjects/VKBD/Main.qml:30:20: Property "y" is custom-parsed in PropertyChanges. You should phrase this binding as "inputPanel.y: window.height..." [Quick.property-changes-parsed]
                y: window.height - inputPanel.height
                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Warning: /home/luchen/Documents/QtProjects/VKBD/Main.qml:29:25: You should remove any bindings on the "target" property and avoid custom-parsed bindings in PropertyChanges. [Quick.property-changes-parsed]
                target: inputPanel
                        ^^^^^^^^^^

            PropertyChanges {
                inputPanel.y: window.height - inputPanel.height
            }