Tutorial
Bootstrap 4 Multilevel Dropdown Menu on Mouse Hover
Implementing bootstrap 4 multilevel dropdown menu on mouse hover instead of clicking by using simple modifications that are supported in most broswers.
Collapsible fixed sidebar in Bootstrap 4 Using Collapse JavaScript plugin
Collapsible fixed sidebar in two columns Fixed-Fluid Bootstrap 4 layout using standard Bootstrap 4 Collapse Javascript plugin through
navbar-togger
button
Implementing two columns Fixed-Fluid layout in Bootstrap 4
Implementing a two columns layout in Bootstrap 4 with one of them fixed in width and height and the other is fluid