Flovit88's description sounds like my experience (I may have added an overly complicated option to that thread ).
One way to do it is to remove the Minimize button from a chart and create a new button which will minimize the chart and perform the necessary actions. And really, if you're using a button, you might as well just hide/show the chart instead.
Maybe if you describe a little more of what you're trying to do, we can suggest a workaround.
Although there is no trigger on mimimize, you can try using OnActivate and OnDeactivate, apparently with combination with some additional conditions. Unless you minimize an object by macro, you have to click on something, that is activate.