ListView: don't stop moving the highlight because of model updates

In QQuickItemViewPrivate::applyModelChanges(), if
moveReason = QQuickItemViewPrivate::Other,
then QQuickItemView::trackedPositionChanged() will fail to call
d->setPosition(pos), which is normally what keeps the Flickable
moving for a while.  Leave the reason as-is (it will be SetIndex in
this case), so as not to forget that we were actually trying to move
down.  Updating the model was just a side-effect of that: either
because some QML code was trying to append to the model or because
fetchMore() was called.

Task-number: QTBUG-61269
Task-number: QTBUG-62864
Change-Id: I3fd402469950d6c12e6a8d6e42be83ea4f54776a
Reviewed-by: J-P Nurmi <jpnurmi@qt.io>

1 files changed, 28 insertions, 0 deletions

diff --git a/tests/auto/quick/qquicklistview/data/appendDuringScrollDown.qml b/tests/auto/quick/qquicklistview/data/appendDuringScrollDown.qml
new file mode 100644
index 0000000000..af35c29143
--- /dev/null
+++ b/tests/auto/quick/qquicklistview/data/appendDuringScrollDown.qml
@@ -0,0 +1,28 @@
+import QtQuick 2.6
+
+ListView {
+    width: 320; height: 240
+    focus: true
+    delegate: Text {
+        height: 40; width: parent.width
+        text: model.text
+        verticalAlignment: Text.AlignVCenter
+        horizontalAlignment: Text.AlignHCenter
+    }
+    highlight: Rectangle { color: "red" }
+    model: ListModel {
+        ListElement { text: "0" }
+        ListElement { text: "1" }
+        ListElement { text: "2" }
+        ListElement { text: "3" }
+        ListElement { text: "4" }
+        ListElement { text: "5" }
+        ListElement { text: "6" }
+        ListElement { text: "7" }
+        ListElement { text: "8" }
+        ListElement { text: "9" }
+    }
+
+    readonly property Item topItem: itemAt(0, contentY)
+    onTopItemChanged: model.append({ "text": "new" })
+}