QmlDesigner: Update GradientDialogPopup Controls 2

* Add background radius property to AbstractButton
 * Use AbstractButton instead of Controls 1 Button for
   GradientDialogPopup
 * Remove a few unnecessary imports

Change-Id: I02e0c5f198bd701d144effc5a574fc247182ffb4
Reviewed-by: Thomas Hartmann <thomas.hartmann@qt.io>

share/qtcreator/qmldesigner/propertyEditorQmlSources/imports/HelperWidgets/GradientDialogPopup.qml

@@ -25,9 +25,9 @@
 
 import QtQuick 2.1
 import QtQuick.Layouts 1.0
-import QtQuick.Controls 1.0 as Controls
+import StudioControls 1.0 as StudioControls
+import StudioTheme 1.0 as StudioTheme
 import QtQuickDesignerTheme 1.0
-import QtQuick.Controls.Styles 1.1
 
 Loader {
     id: gradientDialogLoader
@@ -93,33 +93,12 @@ Loader {
                     text: qsTr("Gradient Properties")
                 }
 
-                Button {
+                StudioControls.AbstractButton {
                     width: 16
                     height: 16
-                    style: ButtonStyle {
+                    buttonIcon: StudioTheme.Constants.closeCross
-                        background: Item {
-                            Image {
-                                width: 16
-                                height: 16
-                                source: "image://icons/error"
-                                opacity: {
-                                    if (control.pressed)
-                                        return 0.8
-                                    return 1.0
-                                }
-                                Rectangle {
-                                    z: -1
-                                    anchors.fill: parent
-                                    color: control.pressed
-                                           || control.hovered ? Theme.qmlDesignerBackgroundColorDarker() : Theme.qmlDesignerButtonColor()
-                                    border.color: Theme.qmlDesignerBorderColor()
-                                    radius: 2
-                                }
-                            }
-                        }
-                    }
                     onClicked: gradientDialogLoader.visible = false
-
+                    backgroundRadius: 2
                     anchors.right: parent.right
                     anchors.top: parent.top
                     anchors.margins: 4

share/qtcreator/qmldesigner/propertyEditorQmlSources/imports/HelperWidgets/GradientPopupIndicator.qml

@@ -25,7 +25,6 @@
 
 import QtQuick 2.1
 import QtQuick.Layouts 1.0
-import QtQuick.Controls 1.0 as Controls
 
 Image {
     id: root

share/qtcreator/qmldesigner/propertyEditorQmlSources/imports/StudioControls/AbstractButton.qml

@@ -33,6 +33,7 @@ T.AbstractButton {
     property alias buttonIcon: buttonIcon.text
     property alias iconColor: buttonIcon.color
     property alias backgroundVisible: buttonBackground.visible
+    property alias backgroundRadius: buttonBackground.radius
 
     implicitWidth: Math.max(implicitBackgroundWidth + leftInset + rightInset,
                             implicitContentWidth + leftPadding + rightPadding)