fix multiple items moving up/down

src/librssguard/gui/feedsview.cpp

@@ -436,13 +436,36 @@ void FeedsView::deleteSelectedItem() {
 }
 
 void FeedsView::moveSelectedItemUp() {
-  for (RootItem* it : selectedItems()) {
+  auto its = selectedItems();
+  auto std_its = boolinq::from(its)
+                   .orderBy([](RootItem* it) {
+                     return it->sortOrder();
+                   })
+                   .toStdList();
+
+  for (RootItem* it : std_its) {
     m_sourceModel->changeSortOrder(it, false, false, it->sortOrder() - 1);
   }
 
   m_proxyModel->invalidate();
 }
 
+void FeedsView::moveSelectedItemDown() {
+  auto its = selectedItems();
+  auto std_its = boolinq::from(its)
+                   .orderBy([](RootItem* it) {
+                     return it->sortOrder();
+                   })
+                   .reverse()
+                   .toStdList();
+
+  for (RootItem* it : std_its) {
+    m_sourceModel->changeSortOrder(it, false, false, it->sortOrder() + 1);
+  }
+
+  m_proxyModel->invalidate();
+}
+
 void FeedsView::moveSelectedItemTop() {
   for (RootItem* it : selectedItems()) {
     m_sourceModel->changeSortOrder(it, true, false);
@@ -459,14 +482,6 @@ void FeedsView::moveSelectedItemBottom() {
   m_proxyModel->invalidate();
 }
 
-void FeedsView::moveSelectedItemDown() {
-  for (RootItem* it : selectedItems()) {
-    m_sourceModel->changeSortOrder(it, false, false, it->sortOrder() + 1);
-  }
-
-  m_proxyModel->invalidate();
-}
-
 void FeedsView::rearrangeCategoriesOfSelectedItem() {
   for (RootItem* it : selectedItems()) {
     m_sourceModel->sortDirectDescendants(it, RootItem::Kind::Category);