Use remote desktop to make iPad/Android tablet/computer as a secondary monitor

[gasolin]

As we know some developers are using a secondary monitor to boost their productivity.
More and more workers are working outside of the office like in a coffee shop and they don't have the luxury to connect to the desktop monitor.

It will be handy to use their iPad/Android/Chrome tablet on hand as a secondary monitor.

Technically its possible by creating a virtual display and streaming the X window to vnc. The issue is the setup effort is too steep for a normal user. Would like to see elementary OS user can toggle a button and start to connect their devices as the secondary monitor.

For example there's an application called Virtscreen that make your iPad/Android tablet/computer as a secondary monitor on Linux, but elementary OS can't run it due to gnome tray icon imcompatibility.
https://github.com/kbumsik/VirtScreen

This task including

1. host a vnc server locally (related to ship a remote desktop app with elementary os #3 ship a remote desktop app with elementary os)
   Ref 1 Ref 2 Ref 3 elementary os specific setting
2. use xrandr to create a virtual display
3. use x11vnc to stream x window to vnc
4. provide a reasonable UI to config it

Reference

• Use a second laptop or headed computer as another monitor via vnc
• https://unix.stackexchange.com/questions/326234/setting-up-vnc-server-and-no-physical-display-ubuntu-16-04-lts

[BAProductions]

Sweet