Startup Idea: Multi-Window Display App

Startup idea to develop an Android application that enables multiple application windows to run and be displayed simultaneously. It will notably allow the simultaneous run of a video player and document viewer.

I am a full time student, and in the course of studying pharmacy I find that my phone is most often my go-to tool for research. However, I often times want to display videos from youtube or a native video player on the same screen simultaneously with a PDF document or text file for reference. Most apps I see that would allow one's phone to do this are proprietary to the device's manufacturer. An application for Android OS that allowed a batch of apps to run and be displayed in window mode at once would be a huge boon.