title: Doesn't see popup menu on combobox
body: <p>I'm trying to set a new style to comboBox in qml and get in trouble my combobox doesn't want to show me drop-down list everything else is fine, here is code</p>
  <p>The code I took from Internet</p>
  <pre><code>T.ComboBox {
        id: _comboBox
        anchors.bottom: _borderedTextboxPoints.top
        anchors.horizontalCenter: _borderedTextboxPoints.horizontalCenter
        anchors.bottomMargin: 10
  
        delegate: T.ItemDelegate {  //! Changing style of items in list
               width: _comboBox.width
               contentItem: Text {
                   text: modelData
                   color: &quot;black&quot;
                   font: _comboBox.font
                   elide: Text.ElideRight
                   verticalAlignment: Text.AlignVCenter
               }
               highlighted: _comboBox.highlightedIndex === index
           }
  
           indicator: Canvas {  //! Changing style of indicator
               id: canvas
               x: _comboBox.width - width - _comboBox.rightPadding - 5
               y: _comboBox.topPadding + (_comboBox.availableHeight - height) / 2
               width: 12
               height: 8
               contextType: &quot;2d&quot;
  
               Connections { //! Changing style on pressed
                   target: _comboBox
                   function onPressedChanged() { canvas.requestPaint(); }
               }
  
               onPaint: {
                   context.reset();
                   context.moveTo(0, 0);
                   context.lineTo(width, 0);
                   context.lineTo(width / 2, height);
                   context.closePath();
                   context.fillStyle = _comboBox.pressed ? &quot;#722ed1&quot; : &quot;#531dab&quot;;
                   context.fill();
               }
           }
  
           contentItem: Text {
               leftPadding: 5
               rightPadding: _comboBox.indicator.width + _comboBox.spacing
  
               text: _comboBox.displayText
               font: _comboBox.font
               color: &quot;black&quot;
               verticalAlignment: Text.AlignVCenter
               elide: Text.ElideRight
           }
  
           background: Rectangle {
               implicitWidth: 120
               implicitHeight: 40
               border.color: _comboBox.pressed ? &quot;#2f54eb&quot; : &quot;#1d39c4&quot;
               border.width: _comboBox.visualFocus ? 2 : 1
               radius: 10
           }
  
           popup: T.Popup { //! Changing style of drop-down list
               y: _comboBox.height - 1
               width: _comboBox.width
               implicitHeight: contentItem.implicitHeight
               padding: 1
  
               contentItem: ListView {
                   clip: true
                   implicitHeight: contentHeight
                   model:_comboBox.popup.visible ? _comboBox.delegateModel : null
                   currentIndex: _comboBox.highlightedIndex
  
                  T.ScrollIndicator.vertical: T.ScrollIndicator { }
               }
           }
        }
  </code></pre>
  <p>That's look like this</p>
  <p><a href="https://i.stack.imgur.com/KTVRn.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/KTVRn.png" alt="enter image description here" /></a></p>