If you collapse a loading tree node the node stays collapsed

If you open a tree node (in any page tree) a request will be sent to the server to load the pages. If you click again on the +/- and collapse the tree before the pages are loaded, the node will collapse but the expansion icon will still be a '-'.

This means you can't see what was loaded.

User can continue by clicking twice on the '-' which will open and close the already loaded pages and will start working properly again.