Checkbox mode is a mode that can be turned on in a file display (it is not a global setting like single-click mode) that displays checkboxes next to each item.
Checkbox mode can be turned on with the command in the Folder drop-down menu. It's part of the folder format and can be turned on permanently for certain folders using the folder formats system.
Checkbox mode changes which files are considered for use in file operations (for example, when you click the Copy Files button):
So in the above screenshot, clicking the Copy Files button would copy the files IMG2154.JPG and Spectrum.mp3 to the destination, but not What's New.docx.
The main advantage of check-box mode is that it provides selection persistence in the view modes where it is normally very easy to deselect files accidentally. Clicking an empty area of the file display (or indeed, clicking any file) will still cause all files to be deselected, but their checked states will not be disturbed. One practical outcome of this is that you can double-click on a file to open it, or select files and drag-and-drop them, without modifying the checked states of any other files in the list.
Let's look at a real-world case: imagine that you want to browse through a folder of your holiday photos, to identify the ones you want to send to your friends.
At the end of this process, you will have viewed all the images in the folder, and the ones that you wanted to keep will still be checked. You can then use Copy Files to copy them to another folder (or alternatively, use the Edit / Invert Selection command to invert the check states, and then delete the files you don't want to keep).
Without check-box mode you would have had to copy or delete each file as you viewed it - this way, you can concentrate on viewing the images, and then copy or delete them as a batch at the very end.
The main points to keep in mind about check-box mode are:
There are two commands in the Edit / Select Other menu that can be useful when in check-box mode:
The image marking function in the standalone image viewer can make use of checkbox mode (if the default option to use a File Collection is turned off). When you tag a file through the viewer in this mode, the file display it came from is automatically placed in check-box mode, and the file in question is checked.