The default method for adjusting the white balance in Final Cut Pro is to 'automagically' set it using the 'Balance Color function. This doesn't give you any manual control over your white balance, nor do you have the option to use white balance creatively. That's why I created this simple plugin: 'Manual White Balance'.
Manual White Balance allows you to manually set the color temperature and tint of your shot using oldfashioned sliders instead of automatic wizardry. It is compatible with FCP 10.4 or higher.