[dev1026] Visual cues to let us know when an ability can be used
If you look at your action bar, you'll notice that an ability that requires 1000 TP to execute is darkened if your TP is below 1000. An ability that you just used that has a cool-down period of 30 seconds is darkened while that clock ticks down to zero. The fact that the button is darkened lets us know that that ability is currently unavailable for use. Therefore we don't bother trying to use it.
This should be expanded in a couple ways. Firstly, if an enemy is outside of an ability's area of effect, the button for that ability should be darkened. Secondly, for abilities that are only usable in certain circumstances (e.g. Pugilist's Simian Thrash, which can only be executed after an attack is evaded), the button should be darkened until its special conditions for use are met.
Basically, the only abilities on our action bar that should be lit up at any given time are the ones that are immediately usable.