I believe the graphical effects on destruction should be set by the actors themselves using the newly implemented variants.
However, capturing currently has no visual effect. This is a little problematic. The attached patch makes structures blink when they are being captured, so that you get a visual clue.
Additionally, the blinking code could be used to highlight a structure in the GUI easily. It does not replace the shading color code but goes alongside it. However, we should probably support different blinking for different players in that case, which might get a little more annoying with this implementation (is a component worth it?)