This property editor contains settings that allow you to refine an Island Heal operation in the texture editor (see Healing Separated Points [Texturing]).
The Island Heal tool heals one or more source islands of a polygon object's UV coordinates to target boundaries that they share with another island. Before the boundaries are healed, either the source island(s) or the target boundaries' island(s) is translated and rotated such that the corresponding boundaries on both pieces are aligned. Then, the two islands are healed together along these boundaries.
This process is repeated for each source island (Though source islands are not healed to each other, even if they share boundaries). Once the operation is complete, you can fine-tune the transformation, both to include scaling, and to transform the target boundary's island if necessary.