Size of pop up window

Hello!

I hope someone can help.

I created pages that I use as pop up windows. They appear when a button is clicked.

I'd like to change the size of these windows: they have the same size as the current background.

There is a field in the page properties to change the size, but it is inactivated. How do I activate it, or is there a way to change the size of the window.

Thanks in advance!!!

Hello!

I hope someone can help.

I created pages that I use as pop up windows. They appear when a button is clicked.

I'd like to change the size of these windows: they have the same size as the current background.

There is a field in the page properties to change the size, but it is inactivated. How do I activate it, or is there a way to change the size of the window.

Thanks in advance!!!