Changing the Color of your Pasteboard
Ever get tired of the gray pasteboard? Here’s how you can change it: Select the Paint Bucket tool (G) from the Toolbox (it’s nested beneath the Gradient tool). Select a new foreground color. Press-and-hold the Shift key, click on the pasteboard, and it will change to your Foreground color. Done!
What is a Pasteboard in photoshop?