[FEATURE] thumbnails type

implemented smart content selection and overlay slides:

__Tasks:__

- [x] implement thumbnails type in datagrid
- [x] gather feedback for my changes
- [ ] submit changes to the documentation


__Informations:__

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| Tests pass?   | no
| Fixed tickets | none
| Doc           | none