This depends highly on context. The Jones intrusion/trespassing test and the Katz reasonable expectation of privacy test are generally used to determine whether

This depends highly on context. The Jones intrusion/trespassing test and the Katz reasonable expectation of privacy test are generally used to determine whether police observations from the curtilage (the area surrounding the house) constitute a search. For example, a Florida appeals court recently ruled that peaking through "a gap accidentally left in a window" was violative of the Fourth Amendment. There's a whole series of window peaking, gate crossing, fielding entering, etc. cases. They tend to turn on the very specific facts of the case, such as whether the police intruded on a private space to look through the window, or whether the occupant sufficiently indicated that the space was private.