Stack Overflow's FAQ has the details regarding, what questions could be asked. But I have seen a couple of instances where people have asked non programming questions but still have gotten lots of upvotes for the questions.
Check out this: How to pick an open source project to join?
While my question, which is actually a technical question, was closed by the moderators as Not a real question: How to design similar app like Google Mail - The story of send?
If anyone encounters some interesting apps/tools & will try to develop similar ones, then they can obviously ask it to the community. After that only they can explore, then implement, and if face problem then ask here. Right?
So anyone can explain me why the 1st one is valid and 2nd is invalid for Stack Overflow?