The Sliced View tab displays an alternative view of items selected in the Main View. It is especially useful with mammalian genes which can span vast regions of genomic sequence but which are comprised mostly of intronic sequence. The Sliced View aims to give you a higher level summary of gene structures by condensing the intronic regions and allowing you to focus on the exons, relative to each other. For details about using this feature, see Changing the Appearance of Tracks Track appearance.
The following image shows how this works. The top panel of the IGB Main View window shows the normal, non-spliced view of a region containing overlapping genes from a human, AGBL4 which contains several very large introns, one of which completely encompasses another gene, BEND5. The Sliced View panel on the bottom shows AGBL4, and then BEND5, but with the intronic sequences reduced to 100bp. The points where the introns were shortened appear as black hash marks in the coordinate axis of the Sliced View tab. Note how the Sliced View makes it easy to see the gene structures, whereas in the main view the exons of AGBL4 are so small it is impossible to even see size comparisons of the exons it contains.
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Another feature that the Sliced View panel supports is finding open reading frames (ORFs) and stop codons. For details on using this function, please see Changing the Appearance of Tracks Track appearance.