`LayerWidget` is probably `SkiaLayer` Primitive

[antongit]

• At the moment there is LayerWidget that behaves more like a Primitive (in respect to DrawList: LayerWidget draws itself at the Foreground by default, all other widgets draw themselves AtCursor).
  Should we move it to the Primitives Category and name it SkiaLayer or Layer?
• When LayerWidget is drawn at Foreground, IsItemHovered doesn't work anymore. Not sure if it was planned like that. In CSS if an element is positioned absolute, it is still interacting with the mouse.

From the CSS specs, just for completeness: The element is removed from the normal document flow, and no space is created for the element in the page layout. It is positioned relative to its closest positioned ancestor, if any; otherwise, it is placed relative to the initial containing block.

The general idea about widgets and primitive (from @gregsn): primitives are used to make widgets, there should be an example of doing so, like: an ExampleWidget that uses Group with primitives, CursorPos etc.

[antongit]

LayerWidgets behaves now like other Widgets.