A flex popup -typically of type title window, is by default 50% of the size of its parent and with hel of PopUPManager, it can be centered when loaded.
What if requirement is to have a fuller size popup window -size of it’s parent container?

• One way is to use fixed height and width
• other way is to resize it wrt it’s parent as

sectionPopUp.width=UIComponent(this.parentApplication).width;
sectionPopUp.height=UIComponent(this.parentApplication).height;

Not to say that first approach of using fixed height and width must be avoided as it will break on different screen sizes.
Approach two seemed more elegant to me .