Make add printer dialog resize-aware

resources/qml/WelcomePages/AddLocalPrinterScrollView.qml

@@ -87,7 +87,7 @@ Item
         {
             id: scrollView
 
-            height: (maxItemCountAtOnce * UM.Theme.getSize("action_button").height) - UM.Theme.getSize("default_margin").height
+            height: childrenHeight
             width: Math.floor(parent.width * 0.4)
 
             ListView
@@ -197,7 +197,7 @@ Item
         {
             id: verticalLine
             anchors.top: parent.top
-            anchors.bottom: parent.bottom
+            height: childrenHeight - UM.Theme.getSize("default_lining").height
             width: UM.Theme.getSize("default_lining").height
             color: UM.Theme.getColor("lining")
         }

resources/qml/WelcomePages/AddNetworkOrLocalPrinterContent.qml

@@ -108,6 +108,12 @@ Item
             AddLocalPrinterScrollView
             {
                 id: localPrinterView
+                property int childrenHeight: backButton.y - addLocalPrinterDropDown.y - UM.Theme.getSize("expandable_component_content_header").height - UM.Theme.getSize("default_margin").height
+
+                onChildrenHeightChanged:
+                {
+                    addLocalPrinterDropDown.children[1].height = childrenHeight
+                }
             }
         }
     }

resources/qml/Widgets/ScrollView.qml

@@ -9,6 +9,7 @@ import UM 1.1 as UM
 ScrollView
 {
     clip: true
+
     // Setting this property to false hides the scrollbar both when the scrollbar is not needed (child height < height)
     // and when the scrollbar is not actively being hovered or pressed
     property bool scrollAlwaysVisible: true