Hi Warren,
Thank you, I'm glad to know you like the new version. This is normal behavior. The New Preview mode changes to Edit Preview mode (the white arrow) automatically after defining a new preview. This is because most of the time one wants to change the position and/or dimensions of the just-defined preview, so this automatic mode change is handy in most cases. This has worked this way since years. In a future version I'll add a new preferences setting to control this behavior. New Preview also changes to Readout mode when you select a preview, since previews cannot be nested (that is, you cannot define a preview inside a preview), so New Preview and Edit Preview are not allowed when the current view is a preview.