I used part of the "Laundry App UI Kit Sketch Resource" design that was designed by Satheesh Kumar at: https://www.sketchappsources.com/free-source/3397-laundry-app-ui-kit-sketch-freebie-resource.html to create a quick prototype

This prototype showcases a new Proto.io feature called Gradients, it’s a new way to create and animate gradients straight in Proto.io. You can now make your UI pop with vibrant linear or radial colors, and bring to life with beautiful animations.

Basic To Do prototype based on: https://www.sketchappsources.com/free-source/3625-basic-to-do-app-design-sketch-freebie-resource.html

This 18 Cool Gradients was designed by Osama Dawood https://www.sketchappsources.com/free-source/3607-gradients-ui-kit-sketch-freebie-resource.html

Showing a random image each time a button is pressed. Project was created using Variables and States

Scrollable Landing Page Design from: https://www.sketchappsources.com/free-source/1975-key-t-one-page-website-template-sketch-freebie-resource.html Top Menu and Side Slider changes (State) depending on the scroll position with the use of variables

Form validation using variables and states

Here is an example of a scrollable data table with vertical and horizontal scroll and a fixed header. Data design: https://www.sketchappsources.com/free-source/3706-datatable-with-horizontal-scroll-sketch-freebie-resource.html