Code review and tidying

interface/resources/qml/ErrorDialog.qml

@@ -17,8 +17,6 @@ Dialog {
     id: root
     HifiConstants { id: hifi }
 
-    property bool destroyOnInvisible: true
-
     Component.onCompleted: {
         enabled = true
     }

interface/resources/qml/LoginDialog.qml

@@ -39,14 +39,14 @@ Dialog {
         implicitWidth: isCircular() ? circularBackground.width : rectangularBackground.width
         implicitHeight: isCircular() ? circularBackground.height : rectangularBackground.height
 
-        property int inputWidth: 500
-        property int inputHeight: 60
+        readonly property int inputWidth: 500
+        readonly property int inputHeight: 60
+        readonly property int borderWidth: 30
+        readonly property int closeMargin: 16
+        readonly property real tan30: 0.577  // tan(30°)
         property int inputSpacing: isCircular() ? 24 : 16
-        property int borderWidth: 30
-        property int closeMargin: 16
         property int maximumX: parent ? parent.width - width : 0
         property int maximumY: parent ? parent.height - height : 0
-        property real tan30: 0.577  // tan(30°)
 
         Rectangle {
             id: circularBackground

interface/resources/qml/controls/Dialog.qml

@@ -15,7 +15,7 @@ import "../styles"
 Item {
     id: root
 
-    property int animationDuration: hifi.effects.fadeInDuration
+    property bool destroyOnInvisible: true
 
 
     // The UI enables an object, rather than manipulating its visibility, so that we can do animations in both directions.
@@ -32,7 +32,7 @@ Item {
     Behavior on opacity {
         // Animate opacity.
         NumberAnimation {
-            duration: animationDuration
+            duration: hifi.effects.fadeInDuration
             easing.type: Easing.OutCubic
         }
     }