Any graphical object can be printed over a white background to
mask parts of objects that lie beneath. This can be useful to
improve the appearance of collisions in complex situations when
repositioning objects is impractical. It is necessary to explicitly
set the layer property to control which objects are masked
by the white background.
In this example the collision of the tie with the time signature is
improved by masking out the part of the tie that crosses the time
signature, setting the whiteout property of TimeSignature.
To do this, TimeSignature is moved to a layer above Tie, which
is left in the default layer 1, and StaffSymbol is moved to a
layer above TimeSignature so it is not masked.