Add the menu actors (buttons, background, titles) to your scene, have them hidden off the side of the scene when it starts, then when the 'menu' button is pressed change (or interpolate) the menu actors positions so they're visible in the scene for the player to use. If you don't want it to pause, don't use the pause behavior and don't build your menu in a different scene.
Create your popup using a group of Actors (most likely on a single Layer of their own). One for the window, one for a "Confirm" button, another for a "Cancel" button, etc. Either Spawn it into screen when you want it to and Destroy afterwards, or Spawn it outside of view initially and just move them into view when needed, then back out.
If you want your Game mechanics to pause while your popup is activated, you have to work that out as well.
edit: Whoops too slow. Now you have two references. You can't muck this up now for sure
So, as you mean, if there's one button on a panel, is the way I constrain the button to this panel like this?
constrain attribute (self.Position.X) to [(current.Layer1.Menu.Position.X)±n], constrain attribute (self.Position.Y) to [(current.Layer1.Menu.Position.Y)±n]
Comments
Hope it makes sense.
Either Spawn it into screen when you want it to and Destroy afterwards, or Spawn it outside of view initially and just move them into view when needed, then back out.
If you want your Game mechanics to pause while your popup is activated, you have to work that out as well.
edit: Whoops too slow. Now you have two references. You can't muck this up now for sure
But another problem has encountered:
How to group different parts of a menu, that once I create a behavior to let them move or what, the behavior would effect to them all at one time?
constrain attribute (self.Position.X) to [(current.Layer1.Menu.Position.X)±n],
constrain attribute (self.Position.Y) to [(current.Layer1.Menu.Position.Y)±n]
or what?
Next time, try it first. After all, it seems like you have the logic + code in mind already. Yeah?
Anyway, glad you got to your solution