Simple, janky and inefficient userscript to change the (client-side) colours of Flowdock flow tabs!
- GreaseMonkey or TamperMonkey browser extension (I've only tested with TamperMonkey in Chrome but in theory it should work with GreaseMonkey in Firefox too).
Open the .user.js file in GitHub, then click 'Raw'. Your browser extension should then offer to let you install/upgrade it.
Once you've added the userscript, reload any open Flowdock windows.
Then you can click on your avatar in the top left which should expose the "Change tab colours" option. Click it, and you're away!
Colour values can be any valid CSS colours or "default" to use whatever random colour Flowdock sees fit.