While working in the latest version of WordPress and trying out different themes I noticed they implemented a theme previewer that shows you what the theme you’re about to select will look like before applying it.
This is great because in previous versions of WordPress you could only see a thumbnail view of the theme, click on the thumbnail and it changed your theme. Now you get an almost full-sized screen that includes your posts with the new theme which allows you to see what your blog will look like with the new theme but not actually having to apply the theme.
While previewing a theme your about to apply, you can either cancel or click on “Activate <theme name>” in the upper right-hand corner of the preview screen and the new theme will be applied.
Below is a screen shot of the theme previewer. I show the Design screen first and then the theme preview screen that pops up allowing you to preview the theme you just selected.
Click on the theme you want which in this case I clicked on the middle theme called Simplifi Dark (Grey).
Another point on this is that you can scroll through your blog posts to not only see what they’ll look like but you can also select a blog post to view in the preview window. One way this can be helpful is to view images you’ve used in the past and what they’ll look like with a different theme – are they too big, etc.