* @return Button background.
*/
public static BufferedImage getFullAlphaBackground(JComboBox combo,
ButtonModel model, SubstanceFillPainter fillPainter,
SubstanceBorderPainter borderPainter, int width, int height) {
TransitionAwareUI transitionAwareUI = (TransitionAwareUI) combo.getUI();
StateTransitionTracker.ModelStateInfo modelStateInfo = transitionAwareUI
.getTransitionTracker().getModelStateInfo();
ComponentState currState = modelStateInfo.getCurrModelState();
Map<ComponentState, StateTransitionTracker.StateContributionInfo> activeStates = modelStateInfo
.getStateContributionMap();