Klaus,
We made some progress today, so I update this post to you:
1. I suggest you use canvas.Flush() instead of canvas.EndDrawing(), the two places are in WorldMapKitRenderLayer.cs line 2928 and 2977, because sometimes it will throw exception that leads to tile not drawn.
2. I found the mouse wheel is not symmetrical during wheel down and up, the reason is that you use custom zoomlevels so that sometimes you will zoom in two zoom levels but you couldn’t zoom out back to the original zoom level. I could provide an override method of MouseWheelCore to fix it if you want to.
3. The really problem is also caused by custom zoom levels, we should support custom zoom levels but the code may have a bug, we are still working on the solution to fix it. The normal zoom levels are designed to be perfect match for the tiles even on the board of the world, so when using WrapDataLine mode, it still can draw full tile. But if using custom zoom levels, the scale list are different, so sometimes one tile will be split by the wrapping data line, one part is black, and the other is drawn normally.
Thanks,
James