Gnome 3 Shell in Ubuntu 15.04 crashes and remains black after using DisplayPort & Activities overview mode freezes

[GT]

Gnome 3 Shell on Ubuntu 15.04 crashes when peforming an action related to the use of an external screen connected via DisplayPort (DP).
Gnome Shell first remains black and then it does not awake from the Activities Overview mode. It seems that it crashes twice before it works again.

How to reproduce:
* Use an external screen connected with DisplayPort of the notebook
* Put the system in sleep mode/hibernation
* Disconnect the cable.
* Open the lid of the notebook so that the system wakes up. Now 3 problems/bugs appear:
(1) The system wakes up, but the display remains black. Nothing happens. One gets the system only back to the login screen if one switches via [Control-Alt-F2] to a console and then switches back via [Control-Alt-F7] to the Gnome login screen.
(2) After logging in, something crashes and the system asks you again to log in. After the second try it works.
(3) Gnome Shell appears, but it is not possible to click on any window in the Activities overview mode. No reaction there. The items in the to bar are working, though. Apparently Gnome Shell crashed or froze. To get around that it is necessary to restart the shell via [Alt-F2 and then type "r"].

Overall, these 3 connect bugs are very annoying. I hope it is possible to fix this/these bugs. If you need further information, please let me know.

System:
Gnome Ubuntu 15.04 (updated to newest versions)
Gnome Shell from PPA gnome3-staging, version: 3.16.3-1ubuntu1~vivid1

[Bruce Pieterse (octoquad)]

Hi GT,

Thanks for taking the time to report this.

Please could you run apport-collect 1495092 from the command line after the crash if you are able to reproduce consistently.

1. Not a 100% sure why this would occur, but it is possible that GDM crashed and then restarted.
2. Interesting, could you let us know what that message is? Maybe a screenshot can help us identify the problem, alternatively text is good enough.
3. You might have hit this: https://bugs.launchpad.net/ubuntu-gnome/+bug/1482397 please mark yourself as affected in that bug report if that matches the problem you experienced.

[GT (gleppert)]

Hi Bruce,

thanks for looking into the bug. Yes, I can reproduce the bug consistently; in the last minutes I tried it twice.

I was running the apport-collect 1495092 twice, once after Alt-F2 "r" and once with "sleep 1m && apport-collect 1495092" so that the command was carried out while the Activity overview blocked. In both cases, apport told me that "No additional information collected".

Is there any other way that I collect more information about the bug?

P.S. I think bug 1482397 does not describe my problem, because there the activities overview was still working. In my situation the activities overview is the (visible) problem.

[GT (gleppert)]

Regarding issue (3) in the row of issues: In fact, only the windows are not clickable so that I do not get out of the Activities overview. However, the close windows button in the overview is working, as are the to menu items (except for the left top "hot corner").

I hope someone has an idea where these issues come from. This bug is quite terrible for daily usage. Thanks!

[Launchpad Janitor (janitor)]

[Expired for Ubuntu GNOME because there has been no activity for 60 days.]

[GT (gleppert)]

This bug entry is still valid as of today (with all recent updates of 15.04)