Fill Mode (Slide Image) [Optional]
The way to fill main image of a slide, default value is the global Fill Mode setting.
'Stretch': stretch main image to fill full area of slide.
'Contain': scale main image and put it all inside at center of slide area.
'Cover': scale main image and let it cover full area of slide.
'Actual Size': keep original size of main image and put it at center of slide area.
'Contain & Actual for Small Image': use 'Contain' for large image and 'Actual Size' for small image.
See layout - slider maker help