"Take a screenshot of the current window" in the Unity sidebar right click menu doesn't work for child windows

[dmiller309]

$ lsb_release -rd
Description: Ubuntu 16.04 LTS
Release: 16.04

$ apt-cache policy gnome-screenshot
gnome-screenshot:
  Installed: 3.18.0-1ubuntu2
  Candidate: 3.18.0-1ubuntu2
  Version table:
 *** 3.18.0-1ubuntu2 500
        500 http://us.archive.ubuntu.com/ubuntu xenial/main amd64 Packages
        100 /var/lib/dpkg/status

How to reproduce:
1. Add gnome-screenshot to the Ubuntu Unity left-side application launcher list.
2. Open the Files application or any other application.
3. File > Properties
3. Right click the gnome-screenshot icon in the Unity sidebar, then click "Take a screenshot of the current window".

What is expected:
gnome-screenshot takes a screenshot and shows it to me.

What happens:
* No screenshot taken.
* I get a spinner whenever my mouse is over the Unity sidebar until I restart Unity.
* Screenshotting any other window (including other windows that would have previously screenshot correctly) will fail when taken using the right click menu on the icon in the Unity launcher.

I originally experienced this problem when attempting to screenshot the "Evaluate Expression" child window of PhpStorm.

[Khurshid Alam (khurshid-alam)]

It doesn't work because it loses the focus of the child window. Quicklist menu doesn't respect global delay parameter( another bug).

1. Run in terminal:
$ gnome-screenshot -w -d 5

2. Click on child window.....wait

3. It will take screenshot exactly after 5 sec.

http://i.imgur.com/Ww9UmKF.png

[Khurshid Alam (khurshid-alam)]

See bug here: #1606974