I want control Excel with my keyboard while using the mouse on Firefox. I need to maximize Excel and I have multiple screens so covering the distance to travel between them is a little annoying.
Windows 7 x64
I take it that you want to do more than just use the scroll wheel in Firefox? The scroll wheel should work to control whatever widow the mouse is hovering over.
I don't think it is possible to give the keyboard focus to one application, and mouse focus to another application.
The term "focusing", in OS, means that the input should be received by a module, a window (called Form) in the Windows environment. By input we understand mouse and keyboard.
The main rule is: one and only one module can be focused.