Looking at the Tiles class (http://www.mapwindow.org/documentation/mapwingis4.9/class_tiles.html) this is not possible.
Tiles layers are always the most bottom layer. If you make them semi-transparent they will blend into the white background. Is that what you want?
A workaround is to have a button on your application to make the tiles visible or not.
Tiles layers are always the most bottom layer. If you make them semi-transparent they will blend into the white background. Is that what you want?
A workaround is to have a button on your application to make the tiles visible or not.