How cv::imshow() breaks _CrtMemDifference()

gistfile1.cpp

#define _CRTDBG_MAP_ALLOC
#include <crtdbg.h>

#include <opencv2/opencv.hpp>
#include "opencv2/core/core.hpp"
#include "opencv2/imgproc/imgproc.hpp"
#include "opencv2/calib3d/calib3d.hpp"
#include "opencv2/highgui/highgui.hpp"


_CrtMemState s1, s2, s3;

int main(void)
{
	_CrtMemCheckpoint( &s1 );
	{
		cv::Mat xx(100, 100, CV_8UC3);
		cv::imshow("win title", xx);
	}
	_CrtMemCheckpoint( &s2 );
	if ( _CrtMemDifference( &s3, &s1, &s2) )
		_CrtMemDumpStatistics( &s3 );

	return 0;
}

Output of _CrtMemDumpStatistics():

0 bytes in 0 Free Blocks.
110 bytes in 1 Normal Blocks.
0 bytes in 0 CRT Blocks.
0 bytes in 0 Ignore Blocks.
0 bytes in 0 Client Blocks.
Largest number used: 30142 bytes.
Total allocations: 30142 bytes.

cv::imread() can't break _CrtMemDifference().