Frustrated by the fact that you can only run a single Flex Builder workspace at-a-time? Well, I did a bit of digging and found several solutions (related to Eclipse, which is the basis for Flex Builder), best summed up in this Stack Overflow question: Open multiple Eclipse workspaces on the Mac.
I didn’t like popping open a Terminal window; and all of the options resulted in multiple instances of the Flex Builder app running, but they were indistinguishable from each other in the Dock or when task-switching. So, I figured out how to fix that.
First, create a copy of your Flex Builder.app. Fortunately (in this case), the app file references files located elsewhere, so it’s pretty small (a few hundred K), so you’re not duplicating the entire app (as you would be with most Mac apps).
Second, rename your copy to whatever you want to call it—I used the name of the workspace.
Third, right-click on the app and choose to Show Package Contents. In Info.plist, change the Eclipse key (which is an array) to include two additional strings (at the end), the first being “-data” and the second being the full path to your workspace, e.g. “/Users/troygilbert/Documents/Flex Builder Workspaces/Acme Dashboard/”.
Now edit MacOS/FlexBuilder.ini. Change the -Xdock:name option from “Flex Builder” to whatever you want the name to be in the Dock.
Last but not least, replace or edit the icons in Resources/flexbuilder.icns with icons of your choosing. Personally, I like to go to Icon Factory’s fine collection of freeware icons and find something whimsical (and memorable) to use. The Futurama icons are quite nice.
Now you can create a shortcut to your new app anywhere you want, or access it through your favorite app launcher, like Google Quick Search Box.