When I move the cursor to the bottom of the screen, the head with the mask appears.
When I move the cursor over the head, the cursor shape does not change and clicking on the head has no effect.
Should the cursor change shape? I tried clicking all over the head and mask, but the mask does not come off...
(EDIT) I found a way to remove the mask consistently: I have to position the mask and the opening in the ceiling in close proximity and then click on the ceiling (the mouse pointer changes to a hand) just below the opening. Only then I can remove the mask....