Any way to use transparency in SCREEN 0?

[TempodiBasic]

That's not possible, as QB64(PE) supports only one physical window per program. However, as finally the contents of a window is just an image, and we can create as many images as our memory allows you could simply go a master/slave approach.

You have a master program which creates and manages the images and react to inputs and a slave program which can be run multiple times . . .

Thanks for the explanation! The master/slave thing is too complicated for me, so it doesn't work.

IMHO a master/slave structure is more complex, 
when I was developing my windows system I used a simple stack structure, in the main I got the inputs (Keyboard & mouse) and the user action went to the window that was at the top of the stack. So the system must manage the stack and let interact the window on the top with the user.
Surely the system can be enpowered with inputs that let navigate quickly from a window to another adjourning the position of the windows in the stack. Take as example the Alt+Tab that let you navigate among the different open window in Windows.
moreover if there are uncovered areas of different windows the pointer of mouse can activate the window pointed (it goes to the top of the stack and it is showed wholly).