If this sounds like your week
Fake overlays intercept input
Hit-testing bugs show up as “I clicked Excel but the border ate it.” Native DWM paths reduce that class.
Where tooling usually breaks
Latency stacks in unexpected layers
Every extra invisible window above the client area is a potential input bug. Prefer OS-drawn emphasis when truthful.
Conceptual call graph
Target: HWND for pinned window Primary: DwmSetWindowAttribute border emphasis Fallback: layered transparent border HWND Invariant: mouse messages → client window