Recently there have been some updates with bug fixes for the user interactions. With version 7.1.5.2, scenes can be moved with the mouse without any problems. Moving the scene list columns used to work with version 7.1.3, but no longer. This is probably a new bug.
You mean a tree view? No, that is not the concept of yWriter. The left hand pane is for chapters, and the right hand pane is for scenes within the selected chapters.
If that's not for you and you don't need the write function anyway, there are free alternatives that you may already be aware of:
I can recommend FreeMind as a quick and easy-to-use outliner.
For comprehensive planning with metadata, storylines and world building, you might want to take a look at oStorybook.
Cheers,
Peter