You can choose a sorting-order for items within the gallery from these two drop-down lists. Items can be sorted by name (alphabetically), by their size in memory, by their size on disk, by the file type, or by the length of their name (depending on the gallery). If the Reversed check box is checked then the items are sorted in the reverse order.

For example, you may have a gallery of bitmaps that you would like sorted according to the type of bitmap, e.g. .BMP or .JPG, and within each category of bitmap, alphabetical order. To sort the items this way choose Sort by file type from the Primary Key list and Sort by name from the Secondary key.