Windows: Add a note about why hidpi is disabled.

src/gui/gsmartcontrol.exe.in.manifest

@@ -24,7 +24,8 @@ Copyright:
 		</ms_asmv2:security>
 	</ms_asmv2:trustInfo>
 
-	<!-- GTK3 applications aren't quite dpi-aware -->
+	<!-- GTK3 applications on Windows do not support fractional scaling
+		(e.g. 250%), making them too small on such displays -->
 	<asmv3:application>
 		<asmv3:windowsSettings xmlns="http://schemas.microsoft.com/SMI/2005/WindowsSettings">
 			<dpiAware>false</dpiAware>