In lots of places I have code like:

alignTool = new DrawingArea(57, 12);
alignTool.addOnDraw(&onDraw);

This was fine in 2.4, but now gets flagged as deprecated. I should be using:

void addOnDraw(bool delegate(Scoped!Context, Widget) dlg, ConnectFlags connectFlags=cast(ConnectFlags)0)

Where is the 'Scoped' template described. I see scoped in std.typecons.

How do I change my code to get rid of the deprecation?