When you publish "Notepad ++" in RemoteApp in Windows Server 2012, Notepad ++ icon isn't displayed.
But, the program starts.
And when you go through remote connections to Windows, the program isn't downloaded and isn't usable.
Special characters in the name of the program (the characters + notepad++.exe) prevents its operation via RemoteApp.
Rename the "notepad++.exe" file to "notepad.exe" on all servers concerned by the RemoteApp collection.
Unpublish the original program.
Once the program unpublished, go to : Tasks -> Add RemoteApp Programs.
Click the "Add" button at the bottom of the list.
Select the "notepad.exe" file.
The new file of "Notepad ++" is published.
Now, the Notepad++ icon appears and the program will always start.
Using remote connections of Windows, the program is downloaded correctly.