Your system information

• Steam client version (build number or date): Dec 15 2022, at 21:27:25
• Distribution (e.g. Ubuntu): KDE neon (Ubuntu 22.04 base)
• Opted into Steam client beta?: No
• Have you checked for system updates?: Yes

Please describe your issue in as much detail as possible:

Game windows of Steam games usually do not have a proper metadata associated with them, making it hard for the desktop environment to identify the game and map it to its desktop file. For instance, Counter-Strike Source has a window class of "hl2_linux", which is nothing the desktop can relate to.

Steam already injects a STEAM_GAME X property on the window, so clearly it is able to add additional information to the window. Steam should set the desktop file name on the window to the desktop file it installed for the game through e.g. _KDE_NET_WM_DESKTOP_FILE or GTK_APPLICATION_ID property.

I am not sure if the file is present if the user chose not to add a desktop/start menu shortcut but at least under Wayland generally apps should always install a desktop file, in doubt as NoDisplay if it shouldn't show up in the menus.

Steps for reproducing this issue:

1. Launch Counter-Strike Source through Steam (affects many other games, too)
2. Try to pin the app to the task bar in Plasma
3. The option is grayed out