Test the key at the window

You look carefully at the window and quickly find the keyhole for the key from the chest. You insert the key and turn it.

Immediately, the window turns into a wide balcony. You walk outside and realize with shock that your shirt has disappeared. You quickly turn to go back inside, but the window has reappeared: you are trapped outside!

Then you realize that the landscape outside the tower has changed. Instead of woodlands, you are surrounded by other towers, also with balconies. And you are very aware that your naked form is on display to all of them. You look around. There is a cot in one corner, but it doesn't have any covers. But lying on it is a, well, dress, for lack of a better word. It is almost transparent--the improvement it offers over being naked seems negligible.

On the other corner of the balcony is a gate--hurray! But as you rush to it, you realize it is locked. You look next to it. You find the strangest outfit: a golden metal hoop that is hinged in the middle and is joined to another translucent dress. But this dress has a second golden hoop as a belt. Looking at it, you realize in shock that both it and the other hoop are meant to be closed, but that there is no obvious way to open them again.

The gate has two panels that match the position of the two hoops. Clearly, you can only leave by the gate wearing the dress.