Nothing worse than writing the proper code, but not seeing the effect.
Then spending hours and hours trying to figure out if it's a bug, if it's your syntax, or if you're not changing the proper thing.
Case in point, learning flex skinning changing the border color of a ToggleButton from black to white, it should be pretty straight forward, look for the border color section and change it's value.
Hmm why isn't this working...
The comment does say border and I'm changing the color from the black hex to the white hex, why is the border still black! maybe the code isn't this part
maybe i should be changing something else
Hours later, OMG it wasn't flex fault, it wasn't my codes fault it was thanks to Firefox and it caching the swf *sigh*
1. Up in the address bar type in "about:config"
2. Change the property browser.cache.disk.enable = "false"
Firefox is the least evil for development, in my experience. You know about shift-refresh, right? Also, firebug is invaluable. If you doubt whether or not your swf is really being reloaded, Firebug can tell you for sure.
That said, there are some MouseEvent based bugs that are only present in Firefox (you'll get extraneous click events and other such fun things). But unless you want to cut out 30% of your users, you will have to address them eventually anyway.