Groups are 'invisible' collections of images.
Lispix will operate on all the images in the group at once, for the buttons in the Group Tool, such as Arrange, Mosaic, Info, and CLUT. This is useful for tiling only a subset of open images.
When Link is ON, Lispix will simultaneously zoom and scroll all the images in the group. This is useful for examining detail in corresponding images, either by turning Scroll On, or by using an image Navigator. Zooming the images when linked like this will not resize the image window and reset the scroll, which are normal actions when zooming an image.
Right-click on the Navigator to put cross hairs on the images.
'Window / Groups...' Opens the Groups Tool.
If the Group Tool is closed, the group still remains intact, retaining the name you gave it initially. You may change the group by opening the Group Tool and selecting that group.
Group - select a group
Images - select images for current group
Link - "attach" images in the group so that they zoom and scroll together.
M+ M- add or remove front image from group
Arrange, Info, etc. - operations to be done on every image in the group.