How do I get my pictures to fill the whole window when I am using group merge or scene cleaner. I have tried fit screen and fill screen. It doesn't allow me to drag and make bigger. My pictures are showing up really small and have a black and white checkered background. So when I go to remove something off of one picture it is adding the black and white checks to the finale picture. I can zoom in but that is not helping with the fact I need the picture to fill the whole window on both the source and final windows.