V-sync is always forced in fullscreen, even with SwapInterval(0) and driver forced-off

Gaming and Visualization Technologies APIs OpenGL
1

I was trying to reproduce this bug I seemingly had in my application, when I noticed that in the simple Wx cube sample, it was basically the opposite instead.
(I removed the conditionals around ShowFullScreen function on lines 491-496 to not get the little non-exclusive window)

I even tried to explicitly set SwapInterval(0) (and trying with both driver “application-controlled” and “disabled”), to no avail.

@@ -18,6 +18,9 @@
 
 // For compilers that support precompilation, includes "wx.h".
 #include "wx/wxprec.h"
+#include <windows.h>
+#include <gl\gl.h>
+#include <wglext.h>
 
 #ifdef __BORLANDC__
 #pragma hdrstop
@@ -381,6 +384,14 @@
             wxLogError("Stereo not supported by the graphics card.");
         }
     }
+	
+	PFNWGLSWAPINTERVALEXTPROC       wglSwapIntervalEXT = NULL;
+	PFNWGLGETSWAPINTERVALEXTPROC    wglGetSwapIntervalEXT = NULL;
+
+	wglSwapIntervalEXT = (PFNWGLSWAPINTERVALEXTPROC) wglGetProcAddress("wglSwapIntervalEXT");
+	wglGetSwapIntervalEXT = (PFNWGLGETSWAPINTERVALEXTPROC) wglGetProcAddress("wglGetSwapIntervalEXT");
+	wglSwapIntervalEXT(0);
+	
     SwapBuffers();
 }

GTX 980, forceware 381.65, W10 CU.
While I can “correctly” see tearing on Win7 with an AMD card.

2

Testcase binaries can be found here.