Which stack exchange site make it possible to ask such a questions?
You may try Web Apps StackExchange.
What topics can I ask about here?
Web Applications Stack Exchange is for expert and advanced users of web applications.
If your question generally covers …
- Using Gmail, Facebook, Twitter, Google, or any other website which behaves like an application
- Features of browsers which are directly related to the use of a web application (Greasemonkey scripts for a web application, etc.)
… then you’re in the right place to ask your question!
Also have a look at gmail tag:
For questions about the Gmail service as accessed by a desktop or mobile browser. Questions about native smartphone apps are off-topic on Web Apps.
Visiting some frequent questions on gmail tag may be useful.