As mentioned in the wiki:
“If there are overlapping segments within a maternal/paternal view of a chromosome, only the front (last drawn) will be pickable. If it is completely obscured, you will not be able to see the details of the hidden segment.”
It seems that they are drawn in the order that the associations appear under the person, is that correct? If so, users could be advised that they can easily change this order (using the up/down arrows in the Associations tab of the person editor) in order to see the segments differently – specifically, to see all of the segments for a particular match, just move that association to the bottom of the list.
More generally, users might want to order the DNA associations of a given person so that the closest relatives are at the top and the most distant relatives are at the bottom, in order to minimize the amount of hidden segments. For example, when a distant relative shares a subset of the same segment as a closer relative, the distant relative’s portion will be hidden if the closer relative’s association is further down in the list. By moving the distant relative further down, their subset will be drawn on top.