How do I use xhost for linking the display of one virtual terminal device to another?

I am currently trying to make an autonomous drone using the Robot Operating System (ROS ). To do this, I have installed **Raspbian Lite** (**Jessie**) on a **Rasperry Pi 3** and am currently using **ROS Kinetic** on it. I decided to go with **Openbox Window Manager** and installed a terminal onto it for convenience. I can just call sudo startx to open up a window manager in another terminal. Since there is no desktop environment, I have also installed **tmux** for convenience. I am running the *xserver* on a particular pane and conduct my *ROS* work on other panes. Now when I try to run commands that call on a GUI application from my first terminal virtual device (Ctrl + Alt + F1), I get the error: QxcbConnection: Could not connect to display Aborted After a recommendation from this question, I decided to install xhost on my terminal emulator (which is running on my window manager on my second terminal virtual device, that can be accessed by Ctrl + Alt + F2). After invoking xhost + in the same emulator, I get this: access control disabled, clients can connect from any host After which I invoke xhost which returns with: access control disabled, clients can connect from any host SI:localuser:root Therefore, in my first virtual terminal device, I have set the environmental variable to 5 different values which have been listed below, and tried to run the program which calls on the $DISPLAY, but I get the same QxcbConnection: Could not connect to display error. SI:localuser:root localuser:root localuser root SI:localuser localhost:0 The last one was actually from the linked question. To my understanding, I am doing exactly what is listed out in this man page. What am I doing wrong? ----- **NOTE** I have also tried ssh'ing into the window manager with ssh root@raspberrypi (which is what I infer the user@hostname to be from the prompt in my terminal emulator inside my window manager). However, this asks me for a password, which I do not know and cannot access. This is the topic for this question.