Werk #15942: Fix default selection of "Tree of folders" snapin

If you added the snapin "Tree of folders" to the sidebar, only the topic dropdown with the default "Overview" was shown. The second dropdown of the view choices was missing.

A workaround was, to change the dropdown to another topic as "Overview". The second dropdown appeared and on change back to "Overview", you could choose a view of this topic.

Note: This only occurs on the first use of the snapin. If you have already selected something, the dropdown values are read from user files.

To the list of all Werks