Any way to keep firefox windows from greying out when not in use?

[iCaleb]

For example if I have two firefox windows open side by side and there both loaded on the the webpage google.

I have to click one window or the other before I can start typing.

How can I keep multiple windows open at the same time without clicking on the one I want to use?

I want to use multiple windows at the same time without any of them being faded out or sleeping.

 

[Bear]

...
I have to click one window or the other before I can start typing.

How can I keep multiple windows open at the same time without clicking on the one I want to use?
...

By default, keyboard input goes to the currently selected window. If you don't want to use the mouse to select the window, use the appropriate keyboard shortcut.

You can check/set what it is in System Preferences->Keyboard->Keyboard Shortcuts under "Keyboard & Text Input".