dynamic maps in Crystal reports - transparent background

In the process of migrating from TB2 to Map we also have to migrate CR reports. A few of them include a map which is created dynamically. For creating these maps with Map/AIMS I use the GeoRest extension (the one which comes with AIMS installation). The Georest extension seems only to be able to create PNG files - including a transparent background. But there is a bug in CR 2011 - transparency is not handled properly and converted either to a black or white background (see Note:  1199393 ). In our case the background was always black - the report with the map embedded didn't look nice at all:

transparent background appears black....

My colleague found a nice work-around. We created a layer which covers the whole area relevant for reporting. The layer is put in the background and gets the colour white. A map generated via GeoRest does not have a transparent background anymore:

....background colour set to white

Map 2013, SP2