The out of the box menu bar that is show with every SharePoint List Form, see below image, does not always provide or look / behave the way one would want.
For example, one your enter Edit Mode by clicking Edit all, there is no way to exit. Even returning the form to View mode does not change the menu bar.
It would be nice to be able to do the following:
Hide the menu bar. This is good if the app will provide it's own buttons to enter edit more and save.
Select the mode. So if in Edit more display Save/Cancel. If in View mode display Edit all. This is helpful if we want to save the form but not close it (This is default OOTB behavior for a SP List form). Yes, we can stop the close but the Menu Bar still says Save/Cancel. Not a good UX.
Change the labels. Change "Edit all" to something list specific.
Hide "Comments" icon.
Close "X" Event
Add additional menu items, and associated events.
These are just a few that I can think of. The basic theme is more control over the ribbon and how the app behaves.