Let us start here, from square one. No, from Zero!

overlay/imgui/extensions.h

@@ -0,0 +1,8 @@
+#pragma once
+
+namespace ImGui {
+
+    void HelpMarker(const char* desc);
+    void Knob(float fraction, float size, float thickness = 2.f,
+            float pos_x = -1.f, float pos_y = -1.f);
+}