Few details change how a room feels as quickly as a beveled glass window. Catch afternoon light on an angled edge in a Leesburg dining room and you get a spill of color and prismatic sparkle that a flat pane cannot produce. For owners of historic Virginia homes, these windows are often original, and for churches and commercial owners they set the tone of the entire building. Yet many of them are leaking air, cracking at the lead, or being swapped for flat glass by people who