System Information

MSVC/Win64/Win32 UNICODE build, using our own build rig (non-CMake-based)

Detailed description

Fix being filed as we speak. imshow() produces view panels with "Chinese garbled windows titles" and possibly other ills once you go for a UNICODE build, rather than an (old skool) ANSI build.
Turns out OpenCV code (highgui/src/window_w32.cpp) assumes a pure ANSI Win32 API usage & build only, which clashes very badly with modern application UNICODE builds, when you include imshow() as-is.

Suspect issues that MAY be related:

• HighGUI: Silent failure and incorrect behavior with non-ASCII window titles (e.g., black window, corrupted title) #27262
• imshow issue in qt6 #26496

Steps to reproduce

Issue submission checklist

• I report the issue, it's not a question
• I checked the problem with documentation, FAQ, open issues, forum.opencv.org, Stack Overflow, etc and have not found any solution
• I updated to the latest OpenCV version and the issue is still there
• There is reproducer code and related data files (videos, images, onnx, etc)