I'm unclear about when to use PopupWindow vs Dialog. Any insight would be much appreciated. Thanks.
They both use the addView() method along with various windowManager methods. The two are similar in that regard.
Dialogs seem to come with more built-in features for interaction, such as handlers and buttons already included in the base class, while PopupWindows come with more built-in methods for positioning them about the screen.
I think that each of them can do exactly the same as the other, but choosing between the two will be a matter of convenience to the programmer with regards to how you want to use the Object. I'm not a phD in computer science, but I do not think there is a significant difference in processing time between the two based on what I saw in their respective class definitions.
My advice: If you want to have greater control over where your View appears on the display, use a PopupWindow. If you want to add more control and feedback between your View then use a Dialog. If you, like me, want master control over everything, I would suggest a PopupWindow since it has fewer user-evident default methods to override.