ReSharper Web Help

The Peek Definition feature is available since Microsoft Visual Studio 2013. It allows you to see source code of a referenced symbol in the editor without opening a new tab. ReSharper in turn adds some extra functionality to this feature.

Place the caret at the symbol you are interested in. Then press Alt+F12 to open the Peek Definition window. You can use all navigation features here. For example, you can invoke the Navigate to menu and see all navigation commands that are available in the current context.
Navigation_and_Search__Peek_Definition_01
If you choose Base Symbols on the Navigate to menu, you get the list of base symbols in the right part of the Peek Definition window. You can click one of these symbols and see its declaration in the same window. It also works for other navigation commands that return multiple results.
Navigation_and_Search__Peek_Definition_02
Along with navigation features, ReSharper analyses the code and provides appropriate context actions and quick-fixes. If you modify a code line, the file is reanalysed.
Navigation_and_Search__Peek_Definition_03

Tip

You can press Alt+F12 or use Ctrl+Shift+Click to open the Peek Definition window.