Minor improvements on icon selector

IconComboBox.qml

@@ -1,12 +1,24 @@
 import QtQuick
 import QtQuick.Controls
 import QtQuick.Controls.Material
+import Qt.labs.folderlistmodel 2.4
 
 ComboBox {
     id: comboBox
 
     property string iconSourceRole
 
+    property bool hasTwoArgumentGetter: model instanceof FolderListModel
+
+    function getIconUrl(index) {
+        if (!comboBox.model)
+            return '';
+        if (hasTwoArgumentGetter)
+            return model.get(index, iconSourceRole);
+        else
+            return model.get(index)[iconSourceRole];
+    }
+
     delegate: ItemDelegate {
         height: 64
         anchors.left: parent.left
@@ -15,18 +27,11 @@ ComboBox {
             anchors.top: parent.top
             anchors.bottom: parent.bottom
             text: model[comboBox.textRole]
-            iconSource: model[comboBox.iconSourceRole]
+            iconSource: comboBox.getIconUrl(index)
         }
     }
     contentItem: IconChooserDelegateLayout {
-        text: comboBox.currentText
-        iconSource: {
-            if (!comboBox.model)
-                return '';
-            const url = comboBox.model.get(comboBox.currentIndex, "fileUrl");
-            if (!url)
-                return '';
-            return url;
-        }
+        text: comboBox.displayText
+        iconSource: comboBox.currentIndex >= 0 ? comboBox.getIconUrl(comboBox.currentIndex) : ""
     }
 }