This is about these preview images in the quick-dialog (new in 2sxc 9.1). If you're researching the automatic thumbnailer, go here.

As of now, there are 3 types of previews
- App thumbnail
- View thumbnail
- Content-Type thumbnail
App Thumbnails

As of now, the convention is to simply create an app-icon.png file in the root folder of the app. This will automatically be used as the thumbnail.
- it must be a PNG file
- it must be named app-icon.png and be in the app-root folder
- it must be square and at least 500x500 pixels in size (it will be automatically resized to the correct size based on the viewing device)
- it should be fully square, so don't cut out the round corners ahead of time - this is done automatically by the view layer and may change in the future
- it should be fairly unique - so that it's easy to visually recognise in a list of apps
View / Template Thumbnails

View-thumbnails are also PNG files in the same folder as the view/template-file.
- it must be a PNG file
- it must be named identically as the template-file, just with the `.png` extension instead of `.html` or `.cshtml`
- it should be square and at least 500x500 pixels in size, and will be dynamically resized as needed
- it should be fully square as the view will add the rounded corners as needed and this could change in future versions of 2sxc
- it should show what the visual output will look like - like the image/text arragement or similar
Content-Type Thumbnails

Content-type thumbnails are only shown in the _Content_ use cases, so they will never appear when using Apps. The thumbnails are specified in the content-type metadata, where you can also translate the name as you need it.
You can do this in the admin UI in the tab Data - as you can see in the following images:

...and...

- it should be a PNG file, but could also be jpg/gif
- it should be stored somewhere in the app-folder
- it should be square and at least 500x500 pixels in size, and will be dynamically resized as needed
- it should be fully square as the view will add the rounded corners as needed and this could change in future versions of 2sxc
- the image should somehow symbolize the content-type as needed