Within the ESO keybindings there is an option for Toggle Window display, bind this to a key and then you can choose when to toggle the display.

This can be useful if you have "autohide" enabled as it allows you to move/resize the Window with this option enabled. With autohide when you press . to free the mouse, the window auto hides. Pressing the toggle key then brings the window back into view to allow you to resize it or press buttons.