How i made it in my game:
Created an Event Sheet just for the popup or if you want to generalize for the game GUI in whole. It would contain the GUI events like mouse over, mouse out mouse click etc.
Using the Function plugin create functions like CreatePopup, CreateMenu etc, that would be responsible for creating all needed objects, with respective Destroy functions , responsible for cleaning up. Creating and destroying things is very fast no problem on that. More or less like that. Of course you should put a variable telling when to update the Gui components.