If it looks like I don't know what I'm doing, it's because I don't. However, I've glazed a few panes since then, and I'm much handier at it now.
And while I'm dreaming about ctrl-z, I sure wish I could tap my fingers and undo the breaking panes of glass. For one, those old panes reflected back little wavy distortions characteristic of old glass. For another, replacing them will cost us more money than we'd like. Finally, missing panes of glass delays the whole project from being completely finished.
But we're still making progress. Undoing. Redoing.