something is a gleam in somebody's eyeused to say that something is being planned or thought about, but does not yet exist 某事物仅仅是某人的一个构想 In those days, CD-ROMs were still just a gleam in the eye of some young engineer. 那个时候,只读光盘还只是一些年轻工程师心中的构想。
→ something is a gleam in somebody’s eye at gleam2(1)