Popup menu outside of a window

Hi everyone,

Could not found an easy solution for that.

My question: What is the best approach when trying to create a menu that will pop out from a window (e.g: Pressing on a button on a window, will open a menu that will start mid window and pass the window bottom border.

My thoughts: child window, transparent, frameless.

Is there a better solution? Also worth mentioning that I need to pass the state from the top window to that window (react)

Thanks for all!