I propose a new module called interactive_selectors.py that provides a simplified interface for selection tools that can have interaction after they are drawn.

• Create new Lasso, Rectangle, Polygon, Ellipse, Span, and Line tools.
• Deprecate the _SelectorWidgets in favor of these new tools, which would have a much simpler interface and consistent behavior.
• Support the ability to have multiple tools on the same axis, a use case we support in scikit-image, and is also provided in PyQtGraph.
• Always blit if available while drawing, and then draw statically when finished if interactive=True (the default).
• All tools will have a "move" handle in the center and other appropriate handles.

I would prefer to close #5751 and start work on this new module.