[Steffest]

There's a split screen zoom in the menu "view" -> "split screen" (Or press tab)

Most of the tools (like flood fill gradient and blur) I find easier to apply the the entire layer and then use selections or masks to only apply it to the area you want.

It certainly not a direct Deluxe Paint clone, more a conceptual successor while keeping a heavy focus on Amiga file formats and pixels.