Ubuntu – Why does the custom launcher open under a separate icon

iconslauncher

I've created a custom launcher file:

[Desktop Entry]
Type=Application
Name=P4V
Comment=Perforce Visual Client
Icon=/usr/lib/p4v/P4VResources/icons/P4-V_128x128.png
Exec=/usr/bin/p4v
Terminal=false
Categories=Development;

And dragged this file to my launcher. However, when I click the icon, it opens the application under a 2nd, different icon (I click the top one, it opens the application under the bottom one):

launcher icons

The bottom icon isn't present until after I launch the application using the top P4v icon that I manually added.

Best Answer

If an application produces a second icon, not being a generic one

If an application generates a second icon in the Unity launcher other than a a grey, generic icon, there must be already an (other) existing launcher, calling p4v in its main command:

An application's .desktop file by definition has a "main" command in the first line, starting with Exec=. This is the command that is run when the icon is clicked in the (Unity) launcher. Apart from that, a .desktop file can have one or more shortcut- sections, available when you right-click on the representing icon in the Unity launcher.

Multiple .desktop files calling the same application in their main command

The symptoms you are experiencing can happen when more than one .desktop file in either /usr/share/applications or ~/.local/share/applications have the same ("main-") command in their first Exec= line, but the files are differently named.

P4v by default should install (and probably has installed) a .desktop file, named p4vasp.desktop in /usr/share/applications.

How to fix
Your problem should be fixed if you remove your own (probably local) .desktop file, then run p4v from Dash and pin it to the launcher.

What if you want to customize the existing launcher?

If you want to change the .desktop file's behaviour or e.g. its icon:

copy the file from /usr/share/applications to ~/.local/share/applications
don't change the file's name
open the file in gedit (drag it over an opened gedit window) and make the changes you'd like
log out and back in, the local version of the .desktop file will overrule the global one.

To revert, simply remove the local one, log out and back in.

Related Solutions

Unity – Why Are There Two Icons for Nautilus in Launcher

Disclaimer: I am not a Linux programmer, and this answer contains modifying files out of your home folder. It works for me, but do it on your own risk.

This problem appears when you configure your Home icon to have a quicklist for your favourite places the way it is described here.

The way to solve it, as written on the Bug 842257 page, is instead of creating a copy of /usr/share/applications/nautilus-home.desktop in ~/.local/share/applications and modifying this copy, rather modifying the original file. So the steps are:

Delete the copy, if there is any: ~/.local/share/applications/nautilus-home.desktop

Open a terminal and write:

gksu gedit /usr/share/applications/nautilus-home.desktop

Add this text at the bottom of the file, save and close.

X-Ayatana-Desktop-Shortcuts=Videos;Documents;Music;Pictures;Downloads
[Videos Shortcut Group]
Name=Videos
Exec=nautilus Videos
TargetEnvironment=Unity

[Documents Shortcut Group]
Name=Documents
Exec=nautilus Documents
TargetEnvironment=Unity

[Music Shortcut Group]
Name=Music
Exec=nautilus Music
TargetEnvironment=Unity

[Pictures Shortcut Group]
Name=Pictures
Exec=nautilus Pictures
TargetEnvironment=Unity

[Downloads Shortcut Group]
Name=Downloads
Exec=nautilus Downloads
TargetEnvironment=Unity

Reboot. It should work now, only one icon, with the quicklist.

If it still doesn't work, you can try Alt+F2, then run

unity --reset-icons

This will reset the icons of the original install on your launchbar, so you will have to repopulate it the way you want.

For getting the original nautilus-home.desktop file back, you can reinstall Nautilus and have the default settings and files:

sudo apt-get install --reinstall nautilus

Unity – Icon Missing When Application is Launched: How to Fix

What will most probably solve your problem is to do the following:

Open the application
When it is running, open a terminal and type:
```
xprop WM_CLASS
```
Then click on the open application window.
The output will look like (example gedit):
```
WM_CLASS(STRING) = "gedit", "Gedit"
```
Use the first part (in this case would be gedit), to compose a line in your .desktop file:
```
StartupWMClass=<string>
```
(replace <string> with the actual (first part of the) output of xprop WM_CLASS, e.g. StartupWMClass=gedit)

Now try again (you might have to log out / in), most likely the application will appear in the launcher under its own icon.

Explanation

When an application starts up correctly from a launcher (.desktop file), but another icon appears with only a generic icon (question mark), it is most likely that the application window and the launcher do not connect for some reason, and the launcher does not recognize the application's window as "his". This is often the case when a script or a non- standard application (-command) is used. In those cases the StartupWMClass= line is often the solution.