By default, items in the buffers and various definitions views are sorted alphabetically according to their name. The options in the Sort panel in the Editor Preferences allow you to change this, as follows:
Leaves items in these lists unsorted. For views which list definitions, choosing this option lists definitions in the order in which they appear in the source code.
Sort according to the item name. This is the default setting.
Sort according to the buffer package or the package of the definition's name.
Sorts items according to the type of the definition, or the attributes of the buffer.