A window assembly for installing in a window framing (also referred to as a “window casing”) of a wall of a building. The window assembly is configured to have a frameless appearance when installed with the finish surround installed around the interior and/or exterior of the window. The window assembly also allows the glass panel to be removed with a minimum of removal of the finish surround, such as without removing any of the finish surround, or only removing the finish surround around several sides of the only one of the interior or exterior of the window. For example, in most cases, only the interior finish surround around the right side and left side of the installed window frame needs to be removed to remove and replace the glass panel. Furthermore, the window assembly includes an integrated drain for draining moisture which leaks into the window assembly.