Change/modify application icon during execution

I want to change the application icon when a button is pressed, or when the app is in a particular state (updating data for example). But I can't find the way to do it.

For example the Steam icon, that when an update is downloading or uploading data have a line of points added to the normal icon of Steam.

I've searched but can not find the way to go.

For example in the case of the Steam icon, and added these lines, superimposing two PNG, the upp开发者_开发问答er transparent background??

Is it possible to completely change the icon at runtime? You mean we have such a square as an icon and pressing a button that becomes such a circle?