Window Component not showing up in Deisgner for QtQuick qml

[Methos28]

My Previously Designed project for which I used Qt Community 5.0.2 but now I have installed Qt Community 7.0.0 but its not showing the main Window component in the design tab for some reason can anyone give any solution to this ?

import QtQuick 2.15
import QtQuick.Window 2.3
import QtQuick.Controls 2.15
import QtQml 2.15
import QtQuick.Layouts 1.15
import "controls"
import QtQuick.Timeline 1.0






Window {

    id: mainWindow
    width: 413
    height: 500
    visible: true
    title: qsTr("Login")
    color: "#00000000"
    //flags: Qt.SplashScreen | Qt.FramelessWindowHint



    property string opac
    property string dur

    QtObject{
        id: verified

        function verify(lbltxt){
            if(lbltxt == "1.0"){
                var component = Qt.createComponent("dashboard.qml")
                var win = component.createObject()
                win.show()
                visible = false
            }

        }
    }

    QtObject{

    }



    Rectangle {
        id: bg
        visible: true
        color: "#181818"
        radius: 10
        border.color: "#00000000"
        border.width: 10
        anchors.fill: parent
        anchors.rightMargin: 0
        anchors.bottomMargin: 0
        anchors.leftMargin: 0
        anchors.topMargin: 0



        CustomTxt {
            id: textPsw
            x: 57
            y: 329
            font.italic: true
            font.bold: false
            font.family: "Century Gothic"
            placeholderText: "Password"
            echoMode: "Password"
        }


        Connections{
            target: user
            function onGetUser(opc, dur){
                opcanime.opacity = 1.0


            }
            function onGetOpac(opc, dur){
                verifylbl.text = "1.0"
                opac = opc

            }


        }


        Label {
            id: verifylbl
            x: 8
            y: 263
            width: 26
            height: 13
            visible: false
            color: "#ebeef2"
            text: qsTr("Login")
        }



        Rectangle {
            id: titlebar
            x: 0
            y: 0
            width: 413
            height: 30
            color: "#181818"
            radius: 10
            border.width: 0
            MouseArea {
                anchors.fill: parent
                property point lastMousePos: Qt.point(0, 0)
                onPressed: { lastMousePos = Qt.point(mouseX, mouseY); }
                onMouseXChanged: mainWindow.x += (mouseX - lastMousePos.x)
                onMouseYChanged: mainWindow.y += (mouseY - lastMousePos.y)

                Image {
                    id: image
                    x: 13
                    y: 8
                    width: 392
                    height: 281
                    source: "../../../../../../test.png"
                    fillMode: Image.PreserveAspectFit
                }
            }



        }

        Rectangle{
            id:opcanime
            x: 57
            y: 375
            color:"#00000000"
            implicitHeight: 20
            implicitWidth: 170
            opacity: 0


            Label {
                id: wrong
                color: "#f50b0b"
                opacity: 1.0
                text: qsTr("Wrong Username or Password")
                anchors.fill: parent
                smooth: true
                font.family: "Century Gothic"
            }



        }


        CustomBtn {
            id: loginbtn
            x: 57
            y: 431
            width: 129
            height: 40
            text: "Login"
            colorPressed: "#c12c313e"
            colorMouseOver: "#782c313e"
            colorDefault: "#2c313e"
            font.pointSize: 8
            font.bold: false
            onPressed: {
                user.login_user(textUsr.text, textPsw.text)


            }
            onClicked: {
                verified.verify(verifylbl.text)

            }


        }
        CustomBtn {
            id: quitbtn
            x: 385
            y: 8
            width: 20
            height: 15
            text: "X"
            colorDefault: "#0046547e"
            onClicked: close()
        }

        CustomBtn {
            id: signup
            x: 228
            y: 431
            width: 129
            height: 40
            text: "Sign Up"
            colorPressed: "#c12c313e"
            colorMouseOver: "#782c313e"
            colorDefault: "#2c313e"
            font.bold: false
            onClicked: {
                var component = Qt.createComponent("signup.qml")
                var win = component.createObject()
                win.show()

            }
        }

        CustomTxt {
            id: textUsr
            x: 57
            y: 263
            font.italic: true

        }
    }


    }

This is my QML code but in designer the window wont show up and because of which i cant design any further please help

This is what I am seeing when I am opening Form Editor