Imperator: Rome Textureviewer Command
This command will open a Texture Viewer GUI - clicking the X in the top right of the window will close it.
The syntax for the textureviewer command is as follows:
Find below working examples of the textureviewer command.
This is the only way to use the textureviewer console command - note that it isn't a toggle command, use the X button in the top right of the newly opened window to get rid of it.