Hi Christian,
Thank you for your interest in Syncfusion Products.
1)
a green cell has an alpha component of 0, where we would expect it to be 255. I am afraid that I was not able to reproduce the issue. The green cell has an alpha component as 255 and not 0. Also I have created a simple sample and it is available in the below link:
http://websamples.syncfusion.com/samples/XlsIO.Windows/69736_1/main.htmPlease have a look at the above sample and if still the issue exists, could you please try reproducing it in the above sample and send us the modified sample so that we could sort out the cause of the issue and provide you a solution?
2)
When a cell has no color set, its backcolor comes in as (255, 0, 0, 0) - fully opaque black.We suspect this issue to be a defect and we thank you for bringing this to our attention. To facilitate tracking the progress of the fix we request you to create an incident with the subject as "Alpha channel of background colors inverted - 69736" in our incident database Direct Trac.
Please let me know if you have any other questions.
Thanks,
Melba