From Castle Software:
Keep it out of the way in the title bar area or let it float wherever you want it. Use the images built in to programs or use your own bitmaps on buttons. CastleBar is easy to configure and easy to use. Quickly add new buttons and configure them to behave the way you want them to. You can even temporarily disable buttons if you don't want them to appear on the tool bar now, but may want them back later at the click of a button. There are times when you want to open a different file with the same program. Adding a separate button would take up valuable space on the screen, so CastleBar allows each button to be configured with multiple parameters. When you click the toolbar button, CastleBar drops down a list of your configured parameters and allows you to choose one. See the CastleBar product page on the Castle Software Ltd web site for more details.