Ziegmaster, for convenience, it should be bound to a hotkey and disabled with the Esc key.
Also, there's this: when the transformation window is open, if you go into the hero menu, city menu, etc., it disappears, but as soon as you go back to the global map, it's still there. You have to close it manually.
All these problems were also present in the original mod. Unfortunately, I have no idea how to fix this. Regarding hotkeys, I think closing it with Esc is feasible, but my attempt was unsuccessful because neither the button nor the window reacts to the esc_pressed event. If I get help with this, the mod will get a nice addition.