Friend: In Gmail how do you see only the emails that are starred and also tagged with something specific?You can have advanced features in your application which will make your power users happy and expose them like something as simple as a tips and tricks list. But the UI should be always targetted for simple usage.
Me: Go to show search options put label:yourlabel in has the words box and select starred in search in drop box. Not very intuitive but you can do it. Its a power user feature
Friend: oh ok
Me: Basically you see all the mails labeled with YourLabelName if you search for Label:YourLabelName
Me: So in advanced search we just say search in starred
Friend: I looked at this screen but then i did not use it
Friend: I did not know the has words as labels
Me: It need not be labels
Friend: Actually does not work quite right when i search label:Umesh
Me: If u say label:umesh then it searches for mails with label Umesh. If you want to search mail from me the operator is from:umesh
Me: You can also do your query using only search operators in the simple search box. in: is for searching in a particular group/box. By group I mean inbox, starred, chats, spam etc. So your query could be in:starred from:umesh label:usability to see all mails from Umesh, labeled usability and were starred
Friend: ah cool it works
Me: There are lots of such advanced features in Gmail which are not out right straight forward. The UI is for simple usage and advanced things like this people like us will figure out; thats the idea. They give tips and tricks on their blog
Friend: But then how did you figure it out in the first place?
Me: If you are "powerful" enough to do such kind of mail searches using the UI you can notice the subtle hints Gmail provides using which you can explore further.
eg As a normal user when you click on a label to view all mails in that label just notice the search box. Gmail gives you the hint that its actually doing a search with the operator label:LabelName. Similarly when you click on trash the search box says in:trash, and when you click on a name in your contacts to see all the conversations you had with that person the search box shows from:ContactName. Actually I first noticed the label hint and then explored more out of curiosity to discover others.
Friend: Fair enough
May 16: Updated with the discoverability point. Thanks to Vinodh for bringing up the point