Popup route takes all the screen

Hello,

I try to make a pop-up with some content that will cover only a part of the screen, in the center (something like modalBottomSheet, but in the center of the screen) that will close if I press outside of it.
I was able to create a class that extends PopupRoute, but the content takes all the screen ( unless I set margins to the container returned by the pageBuilder, but, in this way, the content in the back is shown, but if I click it, nothing happens).

Have anyone any ideas how can I achive what I want ?

Thanks,

Please use showDialog() or alert() instead.