Hi Samson,
I couldn't able to reproduce the first issue that you have mentioned, please check whether you have set "EnableShading" property to true. I have solved your second issue in the sample. Regarding the third issue, could you please elaborate what exactly you are pointing to in the screenshot.
http://help.syncfusion.com/support/Diagram.Web/7.3.0.20/F91511/main.htmRegards,
Dinesh