Best practice for plugin UI

import QtQuick 2.9
import QtQuick.Controls 2.2
import QtQuick.Layouts 1.3
import QtQuick.Dialogs 1.2
import QtQuick.Window 2.3
import Qt.labs.settings 1.0
import MuseScore 3.0

MuseScore {
    menuPath: "Plugins." + qsTr("Plugin Name")
    version: "1.1.0"
    requiresScore: false
    description: qsTr("Create a new score based on exsiting template")
    pluginType: "dialog"
    id: mainWindow // required for setting MS4 properties and closing Window


    Component.onCompleted: {
        // Specific MS4 features
        if (mscoreMajorVersion >= 4) {
            mainWindow.title = qsTr("Plugin Name");
            mainWindow.thumbnailName = "logo.png";
            // mainWindow.categoryCode = "some category";
        }
    }

    onRun: {
        // check MuseScore version
        if (mscoreMajorVersion < 3) {
            mainWindow.visible = false
                versionError.open()
        }

    }

    // Compute dimension based on content
    width: mainRow.implicitWidth + extraLeft + extraRight
    height: mainRow.implicitHeight + extraTop + extraBottom
    
    property int extraMargin: mainRow.anchors.margins ? mainRow.anchors.margins : 0
    property int extraTop: mainRow.anchors.topMargin ? mainRow.anchors.topMargin : extraMargin
    property int extraBottom: mainRow.anchors.bottomMargin ? mainRow.anchors.bottomMargin : extraMargin
    property int extraLeft: mainRow.anchors.leftMargin ? mainRow.anchors.leftMargin : extraMargin
    property int extraRight: mainRow.anchors.rightMargin ? mainRow.anchors.rightMargin : extraMargin
       
    // Signal onClosing on the main Window. This code is executed when the window closed
    // Rem: this generates some warnings in the plugin editor log, but this is ok
    Connections {
            target: mainWindow.parent.Window.window
            onClosing: {
                // do whatever is required to do when the plugin window is closing such as managing the settings
                console.log("onClosing: Saving some date to stettings");
            }
        }
    
    // UI
    ColumnLayout {
        id: mainRow // needed for reference in size computing
        spacing: 2
        anchors.margins: 0

        // Plugin controls
        GridLayout {
            Layout.margins: 20
            Layout.minimumWidth: 250
            Layout.minimumHeight: 200
            columnSpacing: 5
            rowSpacing: 5

            // debug
            columns: 1
            Rectangle {
                color: "yellow"
                width: 400
                height: 300
            }

        } // GridLayout

        // Buttons
        DialogButtonBox {
            Layout.fillWidth: true
            spacing: 5
            alignment: Qt.AlignRight
            background.opacity: 0 // hide default white background

            standardButtons: DialogButtonBox.Ok | DialogButtonBox.Cancel

            Button {
                // some non standard button placed on the left side
                id: special
                enabled: true // add real enabling test
                DialogButtonBox.buttonRole: DialogButtonBox.ResetRole
                text: qsTr("Special")
            }

            onAccepted: {
                //... do the stuff ...

                // and close
                mainWindow.parent.Window.window.close();
            }

            onClicked: {
                if (button === special) {
                    //... do some other stuff ...
                }
            }
            onRejected: mainWindow.parent.Window.window.close();

        } // DialogButtonBox

        // Status bar (delete if not needed)
        RowLayout {
            Layout.fillWidth: true
            Layout.preferredHeight: txtStatus.height
            Layout.margins: 5
            spacing: 5

            Text {
                id: txtStatus
                text: "some status"
                wrapMode: Text.NoWrap
                elide: Text.ElideRight
                maximumLineCount: 1
                Layout.fillWidth: true
            }
        } // status bar

    } // ColumnLayout

    // Plugin settings
    Settings {
        id: settings
        category: "MyPlugin"
        // use alias on whatever UI controls
        //property alias subtitle: subtitle.text
        //property alias composer: composer.text
        //property alias lyricist: lyricist.text
        //property alias copyright: copyright.text
    }

    // Palette for nice color management
    SystemPalette {
        id: sysActivePalette;
        colorGroup: SystemPalette.Active
    }
    SystemPalette {
        id: sysDisabledPalette;
        colorGroup: SystemPalette.Disabled
    }

    // Version mismatch dialog
    MessageDialog {
        id: versionError
        visible: false
        title: qsTr("Unsupported MuseScore Version")
        text: qsTr("This plugin requires MuseScore 3.6later.")
        onAccepted: {
            mainWindow.parent.Window.window.close();
        }
    }

} // MuseScore