If you switch to the Hatching tool, you should see a select box for Floor Style. Changing that value will change the floor to various different textures. There

If you switch to the Hatching tool, you should see a select box for Floor Style. Changing that value will change the floor to various different textures. There isn't exactly a way to do walls like that, but using a second layer, you could choose a different floor style and draw around your floors. I'm hoping to make it possible to add your own floor and hatch styles in a future update.