How to have both monitors in the workspace preview for Gnome Shell?

For my Gnome Shell, I have disabled that Workspaces should be on primary display only. So now, whenever I switch the workspace, both monitors switch their content as they should.

Yet when I press Meta in order to get a preview of my Workspaces, all I see is the preview of the workspace's content of the primary monitor.

This makes navigating my worksapces pretty hard as I have to know on which secondary monitor some window is hiding.

How do I get a prewiew of all monitors' content in the preview?

This is doable with an extension called multi-monitors-add-on.

You can also find it on extensions.gnome.org for installation.

If you are using the latest version of Gnome shell (3.14 and 3.16) use the master branch:

git clone git://github.com/spin83/multi-monitors-add-on.git
cd multi-monitors-add-on
cp -r multi-monitors-add-on@spin83 ~/.local/share/gnome-shell/extensions

For Ubuntu 14.04, which has Gnome shell 3.10, use the gnome-3-10 branch:

git clone git://github.com/spin83/multi-monitors-add-on.git
git checkout gnome-3-10
cd multi-monitors-add-on
cp -r multi-monitors-add-on@spin83 ~/.local/share/gnome-shell/extensions

then restart gnome shell and enable the extension. To enable it, you can use the Tweak Tool.

The result:

The extension has a lot of options including removing panels and such. I turn off the panel on the extra monitors and then leave "Thumbnails-Slider" options turned on.