"Automatically tile windows..." does not describe actual feature
In Window Manager Tweaks --> Accessibility there is a checkbox for "Automatically tile windows when moving toward the screen edge." But if that feature is selected that's not what really happens. Instead, the window is maximized -- it does not tile with other windows on the display, it overlays and completely hides them. The feature description in the "Accessibility" dialog should be: "Automatically maximize windows when moving toward the screen edge."
The feature is enabled by default, and very disconcerting. It is hard for users to find the checkbox to disable it, since the checkbox refers to tiling (not what's happening) rather than maximizing or resizing.