Some loaded background files cannot be roated. In the dialog 'Background objects, the parameters 'Rotate' and 'Transparancy' cannot be edited. Why not?

- Raster graphics like JPG can be rotated, but once exceeding sizes of 5000 x 5000 pixels, they are subject to restrictions, due to the used library. Workaround: Divide the image file, reduce the resolution or rotate them in image editing software.
- Visum can visualize DXF/DWG files, but the used library cannot rotate them. Workaround: Rotate these models in a CAD software.