Adjustable position blocking device for sliding closures

An adjustable position blocking device for sliding closures that firmly attaches to a glass pane of a closure and limits the sliding translation of the sliding panels of the closure. One embodiment comprises an elongated track (30) which adheres to a glass pane with very high bonding double-sided tape (40). The one embodiment also comprises a blocking slider (10) that adjustably attaches to track (30) at a plurality of track positions and is substantially tall to block the sliding translation of the sliding panels. Slider (10) comprises a modular attachment means that permits the slider (10) to be customized with blocking modules (22, 86, 96) of different form and function. In addition, one embodiment comprises a blocking module (96) which integrates an electronic device to detect the opening of a sliding closure and alert a user, a remote device or a remote system.