If one hasn't noticed, the said issue has been unsolved for the past two years to this answered date, according to this issue #4 on GitHub. The description is also very much alike:
If one tries to switch workspaces using the Gnome "hot corner" then one can see all workspaces with all the windows respectively opened in them. I would like a similar display here, while switching workspaces, rather than just a grid of boxes [...]
The current maintainer, zakkak, seems to be aware of this issue from before and even quoted another project that had similar feature.
This one seems more related to what we want to achieve.
The implementation however, seems to be incomplete:
I have tried implementing it but I don't know how to make it centre aligned. Anyone who wants to try and fix/improve it can find the code in https://github.com/zakkak/workspace-grid-gnome-shell-extension/tree/thumbnails. It currently displays both the switcher and the thumbnails for testing purposes.
Several contributors had tried testing the implementation and latest attempt to this date was recorded in early-2016, which noted the limitation in this issue #23.
Incorrect grid scaling #23
As mentioned in #4
screenshot from 2016-01-16 18-09-04 (omitted to avoid hotlinking)
Note that this is using the 'thumbnails' branch.
Note that this answer:
- intends to quote relevant information found in the linked resources;
- assumes that OP is not aware of the issue being discussed on GitHub;
- otherwise is useful for users who are affected by the same issue.
Disclaimer I do not use GNOME and not involved with the project.
TL;DR Try out the 'thumbnails' branch, if you haven't. Review the code and suggest improvements at the project repository on GitHub.