In fact, you just have to use the phrase focus (window) before saying something if you want it to be shown in a specific window. You should not forget to focus back to the main window after that.
In fact, Dannii (who updated the extension) explained to me that refreshing the window should only be used to tell what to do when we need to reconstruct the previous state of the window, and that the activity should not be used to manipulate the game world (because it is supposed to be called when the game window is resized, for example).