macOS has always had the ability to take a screenshot but a few versions ago, the feature was modified slightly so that when you take a screenshot, you get a floating thumbnail of it in the bottom right corner. This feature was also added to iOS where it is far more limited in scope. The floating screenshot thumbnail actually has a purpose beyond being a visual representation of a screenshot having been captured. Here’s how you can use the floating screenshot thumbnail on macOS.
Edit and annotate
If you click the thumbnail, it will automatically open the screenshot in Preview with the annotation tools visible. You can then proceed to edit the screenshot i.e, draw on it, enter text, draw shapes, crop, or resize it. This is basically what happens when you tap the same screenshot thumbnail on an iPhone or iPad. To save the screenshot, click Done. To discard it, click the trash icon.
Move to folder or app
The editing feature is more commonly known because of its iOS counterpart but the floating screenshot thumbnail also lets you save the screenshot wherever you want. If you don’t do anything and let the thumbnail disappear on its own, the screenshot will be saved to its default location, however, if you drag the thumbnail to a different folder in Finder, or just drop it onto an app that can accept the file type e.g., the Messages app, you can save the screenshot to the folder or share it/add/open it in the app.
This feature that allows users to save the screenshot to a different location isn’t as commonly known but it can be fairly useful if you need to occasionally save a screenshot elsewhere. It’s also useful for when you need a screenshot for a particular purpose but do not need to save a copy of it long term. You can simply add the screenshot to the app you intend to use it in, and not have to go back and delete it later.
The thumbnail appears in most cases however if you’ve set macOS to copy a screenshot to the clipboard instead of saving it directly to a file, the thumbnail won’t appear. It’s an unfortunate shortcoming but it’s to be expected since no actual file is being created for you to edit or move. The file is copied to the clipboard so you can paste it into any app that supports the file type with the Command+V shortcut.