A transition is always used between 2 slides.
18 Page Transitions
Importing the .pxs file (Slide Style) into ProShow:
ProShow 4.1 and higher:
1. Double click on the .pxs file you just unzipped.
2. That’s it. Really. ProShow will automatically import it.
3. If you have many slide styles to import, go into the Slide Styles window, click on Manage, then click on Add. You can then select multiple Styles to import all at once.
If you have trouble finding your Styles after you have imported them, double check that your Category, Layers and Aspect Ratio drop down menus are set correctly.
For Example, if you just imported a Style that only works with 3 layers in a 16×9 ratio and you have your categories set to All and your Layers set to All, but your aspect ratio is set to 4×3, you won’t see it.