There are a few nifty little features scattered amongst Genesis products and persistent previews in Genesis Custom Blocks is one of them.
A standard custom block built with Genesis toggles between the data entry form and preview mode. Just like below in the custom Progress Indicator block I built in a tutorial last month:
Sometimes though, the form fields are pretty minimal and are more about block settings/options rather than content or data entry. With these blocks, we often put the fields over in the Inspector (side bar area). With persistent previews, the plugin recognises that all fields are in the Inspector and that the content area is field-free. It therefore just keeps the preview “persistent” and refreshes the preview when you change field data. The below shows the same Progress Indicator block, but with the two number fields in the Inspector.
This doesn’t make sense for all custom blocks, but for those that it does, persistent previews keeps the content editing experience more streamlined.