Inform user to install gnupg-agent if it's not already installed.

[andreimacavei]

This issue affects all functions that uses the private key, such as signing or encrypting.
If the private key has a passphrase, there is no way at the moment for user to enter his passphrase.
This is happening with gpg-agent installed. A similar problem could be found here:
http://stackoverflow.com/questions/17492254/how-to-get-gpg-agent-to-ask-for-passphrase-when-generating-keys-with-gpgme

EDIT: after installing gpg-agent, the system must be restarted in order to display the pop-up window.

[andreimacavei]

The issue has changed but I've kept the original text because if we'll want at some time to use pygpgme to generate a key, the above link contains the way we can get the gpg-agent to work.

The remaining issue for now will be to put gpg-agent as a dependency in the installer and requirements file.

[muelli]

hm. Is that a regular GNOME setup? It shouldn't happen.

[andreimacavei]

muelli, what do you mean by a regular gnome setup ? Also, can you be more specific about what shouldn't happen.

[muelli]

When running a regular GNOME session, an agent should have been spawned for you. I think packages like gnome-session are responsible for pulling all the necessary components in.

[andreimacavei]

@muelli , I am using Ubuntu 16.04 with GNOME Shell 3.18.4 and I have gnome-session installed.

In anycase, I am getting a pop-up window now, but it may be another problem because when the window pops to enter the passphrase, I already see the signing error logged in the terminal window:
gpgme.GpgmeError: (32, 1, u'General error')