4.37: Drawing the Highlight

def drawHighlightBox(boxx, boxy):
    left, top = leftTopCoordsOfBox(boxx, boxy)
    pygame.draw.rect(DISPLAYSURF, HIGHLIGHTCOLOR, (left - 5, top - 5, BOXSIZE + 10, BOXSIZE + 10), 4)

To help the player recognize that they can click on a covered box to reveal it, we will make a blue outline appear around a box to highlight it. This outline is drawn with a call to pygame.draw.rect() to make a rectangle with a width of 4 pixels.