When Visual Studio, when you rename a variable or type the name of a class that hasn't been included, a little box appears under the text. If you hover your mouse over it, it pops open and gives you options to either rename all the variables, or include the missing reference.
I'm sure there's a hotkey to pop this open so I don't have to use the mouse. What is it?
For me it's Shift+Alt+F10. Depending on the VS version and your keyboard settings it might be different for you.
The actual shortcut is shown in the tooltip when you check the "Show shortcut key in ScreenTips" box at the bottom of the Tools\Customize\Toolbars dialog (VS2009). This is among the first things I turn on when installing VS.
Use Shift + Alt + F10 to bring up the Resolve menu when your cursor is on the unresolved item.