Why are the hidden (unselect) Meshes fully selected after I show them again?

posted to: Mesh Hiding

Just to describe the situation: Like in this video you can for example select a part of the Eye and Hide the unselected Meshes. I noticed that as soon as I hide the unselected Meshes and show them again, they are suddenly  also selected with the previous selected Meshes (the eye). So the whole Meshes of the object are selected. This doesn't make sense. Why would they be selected after showing them again, if they were unselected before? (This is kinda partly interrupting the Workflow If one is switching relatively often between the selected and unselected Meshes)

Hope you can understand my question.