Hi DaveS,
Thank you for using Syncfusion products.
You can disable the little downward triangle icon visible in the caption bar by setting MenuButtonEnabled property of DockingManager. Below is the code snippet:
this.dockingManager1.MenuButtonEnabled = false;
Please refer the sample in the below link and let me know if it helps:
http://websamples.syncfusion.com//samples/Tools.Windows/F71874/main.htmRegards,
Subhasheela R