Hi Jonas ,
Thanks for using Syncfusion Products.
Currently we don't have support for combining bitwise DockSide in SetSideInDockedMode .But we made a workaround(Sample) to meet your requirement .I have attached the sample as per your requirements in the following link. Please run the sample and let us know if it helps you.
thank you for your response. This is really tricky to do a docking order for this. But there is missing that the windows should all be same sized and are covering the whole content of the DockingManager without such border in the middle. So that you can see the most of every window.
But instead of this, that was the clue I was locking for! Thanks!