Input Messagebox?

I know that it's possible to make messagebox popups with something like the following:

Messagebox MB_OK "hi how are you"

But is it possible to create a popup messagebox with an input (see attached)? I know how to create and manage a textbox with nsDialogs, but I want to make a messagebox input popup.

Any suggestions?

or

(not to be confused with nsDialogs)