Define StartUpWMClass in Linux desktop file

[Josef.Latt@…]

Bitte die StartupWMClass in der Desktop-DAteio wie folgt ändern:

StartupWMClass=org-openstreetmap-josm-gui-MainApplication

[Don-vip]

Documentation:

​https://specifications.freedesktop.org/desktop-entry-spec/latest/ar01s06.html

If specified, it is known that the application will map at least one window with the given string as its WM class or WM name hint (see the Startup Notification Protocol Specification for more details).

​https://specifications.freedesktop.org/startup-notification-spec/startup-notification-0.1.txt

a string to match against the "resource name" or "resource class" hints. If this key is present, the launchee will most likely not send a "remove" message on its own. If the desktop environment detects a toplevel window mapped with this name or class, it should send a "remove" message for the startup sequence. Note that the class hint is in Latin-1, so the value of this key must be converted to Latin-1 before strcmp'ing it with the window class/name. (Though in all known cases only ASCII is involved so it doesn't matter.)

​https://askubuntu.com/questions/367396/what-does-the-startupwmclass-field-of-a-desktop-file-represent

Modern Linux desktop environments (Gnome 3, Ubuntu Unity, Docky) use the WMClass property to associate windows with the owning application. Many Java-based applications have the problem where the windows created by the application are not associated with the shortcut used to start the application (so the dock contains multiple copies of the same icon).

So the field called StartupWMClass is a string that defines in which class the application is grouped in the Unity Launcher at startup.

You can find out which WM_CLASS your window has got when you type in a terminal:

xprop WM_CLASS

and then click at the window. In case of the gnome terminal the output is as follows:

WM_CLASS(STRING) = "gnome-terminal", "Gnome-terminal"

So all windows with WM_CLASS "gnome-terminal" and "Gnome-terminal" are grouped together.

@naoliv do you confirm that with Gnome 3 the xprop command gives the result suggested in this ticket?

[naoliv]

Both on ​awesome and Gnome 3 I can see this:

$ xprop WM_CLASS
WM_CLASS(STRING) = "org-openstreetmap-josm-gui-MainApplication", "org-openstreetmap-josm-gui-MainApplication"

[Don-vip]

In fact regression of r14253 when I killed Main.

[Don-vip]

In 15283/josm:

fix #18013 - fix StartupWMClass parameter in Linux desktop files

[taylor.smock]

In 18402/josm:

fix #21957, see #18013: Fix StartupWMClass for linux (patch by CjMalone)

StartupWMClass was missing the -gui part of the package for MainApplication.