Unfortunately, the styles for the tools are spread out in the Tools source code. So, in this case, the style is actually in the AnnotEdit.cs file. mCtrlPointBorderBrush and mCtrlPointFillBrush, for example.
Every tool is created through the ToolManager, so if you keep an eye on which is the current tool, when you see something you want to re-shape, you can check which the current tool is and it will be either in there or in a subclass.
Please let us know if you have any other questions.