In art, windows can convey many things. They typically act as barriers between the character and the expansive, and mysterious world just beyond their reach. Having a character longingly peering out of them can also express a deep desire to escape or for freedom.
Yoisaki Kanade (from Project SEKAI) certainly looks anxious to get a closer look at what lies beyond her window.
Have any of the illustrations below left you longing to see more?