Make folders expandable in the file display: This option enables the folder expansion feature. If this is turned off, folders won't be expandable at all.

Extra expand button width: Allows you to add configurable padding to the folder expansion button, which may make it easier to click.

Expand deeper level with Alt+click on expand button: If enabled, Alt+click on a folder's expansion button repeatedly expands a deeper level of folders every time. That is, the first click expands the folder as normal, the second click expands all its sub-folders, the third click expands all their sub-folders and so on.

Hide expand buttons until a folder is expanded: This option lets you enable folder expansion without the expander buttons taking up space until they're actually needed. Because the expanders start out hidden, if this option is on the only way to expand a folder is to run the Go EXPANDBRANCH command. For example, you can assign that to a hotkey or toolbar button, and use it to initially expand a folder. Once one folder has been expanded the expander buttons will stay visible until the folder is changed or refreshed.

Save space when no folders are present: Hides folder expanders when there are no sub-folders present in the file display.

Use inline sub-folder color for parent folders: Controls whether or not expanded sub-folders are shown with the same background color as their inline contents.

Clear selections within collapsed folders: When an expanded folder is collapsed, any items within it that were selected have their selection status cleared (so that when you expand the item again they will be unselected).

Collapse sub-folders within collapsed folders: When an expanded folder is collapsed, any expanded sub-folders within it are also collapsed (so that when you expand the item again they will be unexpanded).

Collapse deepest level with Shift+Alt+click on expand button: Shift+Alt+click on a folder's expansion button repeatedly collapses the deepest level of expanded folders under that item.