DwmRegisterThumbnail unable to capture browser when its on background

Question

Im using the winapi DwmRegisterThumbnail to capture the browser thumbnail to my GUI, however when i move the browser to background it stop rendering the thumbnail, my thought its a browser setting to reduce use of resources or something like?

If i move the mouse over the browser at the taskbar, it creates the thumbnail and start capturing it, however as soon the thumbnail is closed it stops capturing.

It only happens on browsers (tested chrome, edge and opera), i also have tested many other applications and i was able to capture the thumbnail correctly even when these windows was on background.

Does someone know something about it?

Answer 1

I was able to solve it by changing the flag:

chrome://flags/#calculate-native-win-occlusion

From "default" to "disabled".

source: https://www.reddit.com/r/incremental_games/comments/l1eec1/psa_disable_window_occlusion_calculation_on/

Thank you zett42 for pointing it!