Hi Gaia,
The Docked controls Splitter color can be changed using DragSplitter object.
We can change the splitter color by setting
DragSplitter.BackColor = Color.Red.
Herewith i have attached the sample for your reference. Please go through the sample and let me know if you have any queries.
Thank you for choosing the syncfusion product.
Regards,
Malarvizhi.
Docking1.zip