This is a sort of magic metablock. Suppose you're using Boost and you have a whole bunch of blocks making a course page longer than it should be, or cluttering up your Dashboard.
Using Multiblock you can collect all those blocks together and use 'one block's worth' of space and put all those blocks into the one space with one of several layouts, whether it's tabs or an accordion, or something else. Several preset layouts are bundled with Multiblock.
Show and tell time, I guess. Screenshots from 3.6 with Boost with the accent colour changed.
Tabbed layout:
Vertical tabbed layout (left)
Vertical tabbed layout (right)
Accordion layout:
Dropdown layout:
Tabs with columns inside it:
There's also some 2-column layouts where the 'multiblock' container has no title so it integrates better into the look and feel. The styling is designed for Boost so mileage with other themes will absolutely vary.
2 column (equal width):
2 column (66% / 33%):
2 column (33% / 66%):
And now a 3-column equal width layout:
If you find a bug, please use GitHub to file an issue - they should be added to https://github.com/arantor/moodle-block_multiblock/issues
Please note that I make no guarantees around resolution times and if you need something more concrete in terms of resolutions, or development, please contact Catalyst IT Europe to discuss your needs.