Image transitioning

[thisisalogin]

Right now, I'm working off of something like eePanels (For those of you who don't know what eePanels is, Its adds transparent images to the side(s) of the interface, Which serve no in-game purpose, but look nice) I would like to have it as such to when A player casts a spell (At this point, The spell type is arbitrary) an image glows. So my question would be, Is there a function to 'glow' is there a library to make something 'glow' or should I just transition through .tga files?