I just installed Ubuntu LTS (20.04.3, Gnome). I see that in my task bar, when I have multiple windows open, it shows multiple dots next to the application icon -- the number of dots supposedly corresponding with the number of windows I have open for that application:
I have noticed, however, that not all windows are accounted for. Terminal (3rd from bottom) correctly shows 2 windows. But Brave browser (top) only indicates one window ... but I have two open. And IntelliJ IDEA (IDE, 2nd from top), shows nothing but I have a window open. Alt+Tab correctly shows all of these windows.
I've figured out that if I open a window from the task bar, it is "counted" and shows on the side. But if I open the window from within the application, it is not. This becomes irritating because I can't switch to the correct window necessarily via the task bar, but instead have to hunt through the many open windows I have via alt+tab. (I don't have so many in this screenshot, but I'm in the process of shutting stuff down to finish the software update; usually I have way more.)
If I right click on one of the icons in the task bar, the 'All Windows' list only shows the windows that were opened from the task bar, not all the windows currently open for the application. Eg. Brave shows one window in 'all windows', terminal shows 2, IntelliJ shows none as if the application were not open at all.
Is there a way to change this behavior so that all open windows are accounted for on the task bar?