void cvui::window(cv::Mat& theWhere, int theX, int theY, int theWidth, int theHeight, const cv::String& theTitle)

[zhaTai]

cvui.h line 2108

cv::rectangle(aOverlay, theContent, cv::Scalar(0x31, 0x31, 0x31), 1);

OpenCV(3.4.4) Error: Assertion failed (res != 0) in cv::Mat::elemSize

delete this line and program is ok

[Dovyski]

Thank you for your bug report! I'll check that error.

[chris-shenzhen-china]

I donwload the new version of cvui，but "cv::rectangle(aOverlay, theContent, cv::Scalar(0x31, 0x31, 0x31), 1); "still in cvui:window.