Neither of these are bugs, so I've removed the bug-report tag etc.
For the folder tree, there are various options for when/how/whether it scrolls horizontally, under Preferences / Folder Tree / Options. Each enables a different mode of the standard Windows tree control, and isn't something custom Opus does.
Under Horizontal scrolling style, you might want the "Manual scrolling only" or "No scrolling or scrollbar at all" options.
For the thumbnails/images toolbar, turn it off under Preferences / File Display Modes / Toolbars.
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