Shell – How to stop a stickied application from launching new instance if already running

applicationdesktop-environmentgnomegnome-shellgnome3

I have a program that I have written in Python and added to Gnome with a desktop file. When I click the stickied icon in Gnome to launch it, it duplicates the icon on my task bar and opens a new instance. Other stickied applications just get a line under them. When you click these other applications (like Chrome or Sublime Text) and they are already running, gnome just jumps to their window instead of launching a new instance.

Is this behavior something that I need to handle in my application, or is this something that Gnome can handle for me? It is a PyQt4 application with a bash launcher if that makes a difference.

Edit- Forgot to mention that I am running Ubuntu-Gnome 16.10 with Gnome 3.20.4

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I got this to work.

You need to add the key 'StartupWMClass' to your desktop entry.

StartupWMClass: 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.

Protocol information here with more details here.

You can install xprop, run it and click the title bar to find out what class your application is.

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So, apparently my second edit wasn't correct: the way it GNOME Shell determines application grouping isn't the one I described.

After asking on the IRC gnome-shell channel, user halfline provided me the policy for grouping applications into Dash icons:

_GTK_APPLICATION_ID property of the window matched to the desktop file id or WM_CLASS matched to the desktop file id or _NET_WM_PID matched to the desktop file started or StartupWMClass in the desktop file matched to WM_CLASS on the window

He also suggested that it may be possible to change firefox WM_CLASS, and he's right, as there is a --class flag for firefox that allows to change it.

Here's an example:

$ firefox &
$ xprop WM_CLASS
WM_CLASS(STRING) = "Navigator", "Firefox"

Using that flag I get

$ firefox --class "Trello" &
$ xprop WM_CLASS
WM_CLASS(STRING) = "Navigator", "Trello"

which it just have to match the desktop file ID. Now icons are correctly grouped.

Also, note that epiphany has the support to create desktop apps, handling correctly the links with the default browser, therefore for my original purpose it is even better than firefox.

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