The editing toolbar helps you do common things quickly, and is shown here:
Hovering over any of the buttons will show a hint about its function.
Save Now - Save any pending changes to current file.
Save As - Prompt for a new filename to save a copy of (you can change filename and directory).
Save New Version - Add a new version # to the file name and save a new file (preserves original file).
Create and Save Thumbnail - Applies File -> Create Thumbnail settings to create a new thumbnail with current settings, and saves as new file, and copies thumbnail filename to clipboard.
Print Image - Show print dialog to enable printing of current image.
Undo - Ignore the last operation.
Launch Graphic Editor - Launches any configured third party graphic editor (see configuration here).
Unselect All - Deselects any current selection.
Resize - Brings up quick resize menu.
Add Border - Adds one of many different border styles to the image.
Add Shadow - Adds a shadow to the image using current shadow options (see also help section on working with transparency).
Crop - Crops the image to the currently selected region.
Blur Inside Region - Blur, Diim, Grey anything inside the current region - useful for hiding info.
Blur Outside Region - Blur, Dim, Grey everything outside the currently selection region - useful for drawing attention to some info.
Object Editing Tools - See the help section on working with object.