For Round Corner you need to enable
Settings -> Document Properties -> Set Styling Mode as Advanced
If you click on the chart then the Chart will be in active state and if you click outside the chart then it is automatically inactive, I am not sure why you are trying that with button.
In case if you need to change the button then you can do it by using variable with button and calculated expression for color.
Hope this helps you.
As the settings you are referring to relate to the caption, if you aren't seeing any change perhaps you are simply forgetting to turn the caption on? I've not had a problem with getting different colors to display for active / inactive captions. If you want the background color of the button or text object to change then apply Jagan's suggestion.