Event based or loop based is separate from retained or immediate.

The canvas api in the browser is immediate mode driven by events such as requestAnimationFrame

If you do not draw in WM_PAINT it will not redraw any state on its own within your control.

GDI is most certainly an immediate mode API and if you have been around long enough for DOS you would remember how to use WM_PAINT to write a game loop renderer before Direct2D in windows. Remember BitBlt for off screen rendering with GDI in WM_PAINT?

https://learn.microsoft.com/en-us/windows/win32/direct2d/com...