Replace "transparent" Rectangles by Items

plugins/ImageReader/ConfigUI.qml

@@ -156,11 +156,10 @@ UM.Dialog
                     anchors.verticalCenter: parent.verticalCenter
                 }
 
-                Rectangle {
+                Item {
                     width: 180
                     height: 20
-                    Layout.fillWidth:true
+                    Layout.fillWidth: true
-                    color: "transparent"
 
                     Slider {
                         id: smoothing

resources/qml/AddMachineDialog.qml

@@ -74,10 +74,8 @@ UM.Dialog
                 width: machineList.width
                 style: ButtonStyle
                 {
-                    background: Rectangle
+                    background: Item
                     {
-                        border.width: 0
-                        color: "transparent";
                         height: UM.Theme.getSize("standard_list_lineheight").height
                         width: machineList.width
                     }

resources/qml/JobSpecs.qml

@@ -9,7 +9,7 @@ import QtQuick.Layouts 1.1
 import UM 1.1 as UM
 import Cura 1.0 as Cura
 
-Rectangle {
+Item {
     id: base
 
     property bool activity: Printer.getPlatformActivity
@@ -29,7 +29,6 @@ Rectangle {
     property variant printMaterialCosts: PrintInformation.materialCosts
 
     height: childrenRect.height
-    color: "transparent"
 
     Connections
     {
@@ -84,9 +83,8 @@ Rectangle {
                 }
                 style: ButtonStyle
                 {
-                    background: Rectangle
+                    background: Item
                     {
-                        color: "transparent"
                         UM.RecolorImage
                         {
                             width: UM.Theme.getSize("save_button_specs_icons").width;

resources/qml/Legend.qml

@@ -9,14 +9,13 @@ import QtQuick.Layouts 1.1
 import UM 1.1 as UM
 import Cura 1.0 as Cura
 
-Rectangle {
+Item {
     id: base
 
     UM.I18nCatalog { id: catalog; name:"cura"}
 
     width: childrenRect.width
     height: childrenRect.height
-    color: "transparent"
 
     Connections
     {

resources/qml/MonitorButton.qml

@@ -10,13 +10,11 @@ import QtQuick.Layouts 1.1
 import UM 1.1 as UM
 import Cura 1.0 as Cura
 
-Rectangle
+Item
 {
     id: base;
     UM.I18nCatalog { id: catalog; name:"cura"}
 
-    color: "transparent"
-
     property bool printerConnected: Cura.MachineManager.printerOutputDevices.length != 0
     property bool printerAcceptsCommands: printerConnected && Cura.MachineManager.printerOutputDevices[0].acceptsCommands
     property real progress: printerConnected ? Cura.MachineManager.printerOutputDevices[0].progress : 0

resources/qml/SaveButton.qml

@@ -8,12 +8,10 @@ import QtQuick.Layouts 1.1
 
 import UM 1.1 as UM
 
-Rectangle {
+Item {
     id: base;
     UM.I18nCatalog { id: catalog; name:"cura"}
 
-    color: "transparent"
-
     property real progress: UM.Backend.progress;
     property int backendState: UM.Backend.state;
     property bool activity: Printer.getPlatformActivity;
@@ -55,7 +53,7 @@ Rectangle {
         text: statusText;
     }
 
-    Rectangle{
+    Rectangle {
         id: progressBar
         width: parent.width - 2 * UM.Theme.getSize("default_margin").width
         height: UM.Theme.getSize("progressbar").height
@@ -66,7 +64,7 @@ Rectangle {
         radius: UM.Theme.getSize("progressbar_radius").width
         color: UM.Theme.getColor("progressbar_background")
 
-        Rectangle{
+        Rectangle {
             width: Math.max(parent.width * base.progress)
             height: parent.height
             color: UM.Theme.getColor("progressbar_control")
@@ -75,14 +73,13 @@ Rectangle {
         }
     }
 
-    Rectangle{
+    Item {
         id: saveRow
         width: base.width
         height: saveToButton.height
         anchors.top: progressBar.bottom
         anchors.topMargin: UM.Theme.getSize("default_margin").height
         anchors.left: parent.left
-        color: "transparent"
 
         Row {
             id: additionalComponentsRow

resources/qml/SidebarHeader.qml

@@ -201,13 +201,12 @@ Column
             color: UM.Theme.getColor("text");
         }
 
-        Rectangle
+        Item
         {
             anchors.verticalCenter: parent.verticalCenter
 
             width: parent.width * 0.55 + UM.Theme.getSize("default_margin").width
             height: UM.Theme.getSize("setting_control").height
-            color: "transparent"
 
             ToolButton {
                 id: variantSelection

resources/qml/SidebarSimple.qml

@@ -25,14 +25,13 @@ Item
     Component.onDestruction: PrintInformation.enabled = false
     UM.I18nCatalog { id: catalog; name:"cura"}
 
-    Rectangle
+    Item
     {
         id: infillCellLeft
         anchors.top: parent.top
         anchors.left: parent.left
         width: base.width * .45 - UM.Theme.getSize("default_margin").width
         height: childrenRect.height
-        color: "transparent"
 
         Label
         {
@@ -217,7 +216,7 @@ Item
         }
     }
 
-    Rectangle
+    Item
     {
         id: helpersCell
         anchors.top: infillCellRight.bottom
@@ -225,7 +224,6 @@ Item
         anchors.left: parent.left
         anchors.right: parent.right
         height: childrenRect.height
-        color: "transparent"
 
         Label
         {
@@ -463,7 +461,7 @@ Item
         supportExtruderCombobox.updateCurrentColor();
     }
 
-    Rectangle
+    Item
     {
         id: tipsCell
         anchors.top: helpersCell.bottom
@@ -471,7 +469,6 @@ Item
         anchors.left: parent.left
         width: parent.width
         height: childrenRect.height
-        color: "transparent"
 
         Label
         {