In both Error and Success that button is assigned the Default Role (Depending on Windows version it has a Dark Black border or highlighted Orange, etc) which means it is activated with the Enter Key, so really it has no need for focus which just gives it the dotted outline and allows spacebar to also activate it.
One issue I have in the same region though is the block the button and tip are in appears to be some type of panel instead of just drawing the button and label in the window. This Panel appears to have a background set to a transparent/null brush and whatever text is under the compile window shows through until the button and tip are drawn which looks odd.