The overlay service can overlay painted areas over a Window.
Currently, only one overlay method is supported (Area), but additional methods may be added in the future.
Overlays are created with the CreateOverlay command. This command returns a overlayID, which must be used when removing the overlay with RemoveOverlay.
When creating the overlay, you must specify where the overlay should be inserted into the list of overlays. It is possible to insert the overlay in the front of all others, behind all others, or above/beneath a specific overlay in the list.
Currently, the only supported overlay method is AREA. In this mode, you define an area of the document to be painted in a certain color. A border and grid color may also be specified.
Create a new overlay.
Remove a specific overlay, or, if no overlay ID is specified, remove all overlays for the given window.