Fix child selection in multi-selection generic wxTreeCtrl.

The children which are not currently shown on the screen shouldn't be affected
by Shift-selecting in multi-selection control.

Closes #1312.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@70249 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/generic/treectlg.cpp

@@ -2054,7 +2054,8 @@ wxGenericTreeCtrl::TagAllChildrenUntilLast(wxGenericTreeItem *crt_item,
     if (crt_item==last_item)
         return true;
 
-    if (crt_item->HasChildren())
+    // We should leave the not shown children of collapsed items alone.
+    if (crt_item->HasChildren() && crt_item->IsExpanded())
     {
         wxArrayGenericTreeItems& children = crt_item->GetChildren();
         size_t count = children.GetCount();