There is a very handy feature in Visual Studio which when turned on ensures the solution explorer is synched with the main editor window, i.e. whichever field is opened in the main editor window is also selected in the solution explorer. I think this is is the default behavior of VS but in case it turns off on you (as happened to me, found it very frustrating) here is how to turn it back on.
2. Make sure ‘Show all settings’ is ticked then
3. Projects and Solutions>General
4. Now tick ‘Track active items in Solution Explorer'”