In Gnome3 one can add applications to the favorites (i.e. pinning the icon on a bar) the same way as in Windows 7:
- start the application
- right-click the icon in the bar of currently running applications
- select "pin" (or "attach" or whatever it's called) in Windows / select "add to favorites" in Gnome3
However this does not work with BSS. There is no "add to favorites" option in the context menu. Other electron based applications do not suffer this problem. My desktop file (which is required to have a launcher icon for BSS in the list of all available applications) is similar to the one in this post.
edit: To be more precise - the launcher icon for BSS in the list of all available application DOES have the "add to favorites" option in the context menu. But that way the application starts and shows up as 2nd icon in the list of currently running applications. And its that icon that does not have the "add to favorites" option. I guess that the "BootStrap Studio" executable launches another process for BSS and that's why we end up with 2 different icons, of which the icon that represents the really running process cannot be added to the favorites.