A windowpane system (101) comprising: a windowpane (102); and at least one primary light source (105); each primary light source (105) being arranged so that light (106) from the primary light source (105) passes into the windowpane (102) through a first surface of the windowpane (102), the light (106) then travelling within the windowpane until it has undergone total internal reflection from one or more second surfaces of the windowpane a plurality of times, wherein at least some of the light from the primary light source is absorbed by the windowpane as the light from the primary light source passes through the windowpane.