The mouseX and mouseY variables are local to your processing project, and wouldn't know where the undercoated frame is relative to your monitor. For example if your mouse is at 10, 10 in the window, that should place your window in the top left of your screen. It's an issue with the local vs global location of the mouse.

I think to be able to drag your window around, you would need to calculate the distance you have moved from where you initially clicked down. So rather than setting your frame position to match the mouseX and mouseY, move the frame location to match the amount you have moved your mouse. Using the mouseDragged() method would work well for this.

Does that make sense?

ak

Thanks for the hint!

I would try first and let you know  if I got success or not.

Thanks again 

thanks again :)