Creating a second window in iPlug2

Is it possible to create a second gui window with iPlug2?
I want to have a second window with a custom control in it. This window needs to be resizable like in the IPlugResponsiveUI example.
Is it possible to do it with iPlug2 or I need to include some external library for the second window?

iPlug2 is currently designed for a single window UI.

OK thanks, I hope in the future it will be possible to create sub windows.