@sismeiro:
Thanks for explaining these three use cases!
@lauren:
Thanks for the explanation. I hope you don’t mind me delving a bit deeper into this:
Do you have a name for the timeline that is above the ‘Source’ and ‘Project’ tabs? For lack of a better name that I know of (told you, I’m still a newbie) I’ll refer to it as ‘Resulting timeline’ (‘Player timeline’ seems intuitive as well, though):
I think that what you allude to in
Edit: Another purpose of the playlist is so you can create a project entirely through that and export from there instead, without having to load it into the timeline.
is the confusing part for me: there are two kind of ‘projects’ possible in Shotcut.
- Playlist projects (sismeiro’s use case 1)
- Timeline projects (sismeiro’s use cases 2 & 3)
As an illustration, suppose that I have added clip 1A and 1B from Source 1 to the ‘Playlist’ UI element. Nothing is added in the ‘Timeline’ UI element.
When I double click a Playlist item (same as choosing ‘Open as Clip’ from context menu), the ‘Resulting timeline’ shows the timeline of Source 1, with the items blue bar indicating In and Out point. This action also results in the ‘Source’ tab becoming the active tab.
When I choose ‘Goto’ from the context menu, the ‘Resulting timeline’ shows the timeline of the Playlist project, with some numbers marked to denote the starting point of each Playlist item. (In the default Fusion Dark theme on my Mac, the numbers are white text on blue background. The numbers are the IDs of the items in the Playlist.) This action also results in the ‘Project’ tab becoming the active tab.
Clicking on the ‘Source’ tab results again in the ‘Resulting timeline’ showing the timeline of Source 1.
But after this clicking on the ‘Project’ tab results in a black box in the Player and an empty ‘Resulting timeline’, whereas I would expect the ‘Resulting timeline’ to show the timeline of the Playlist project again.
Now, when I add 1 of the clips, e.g. 1B to the ‘Timeline’ UI element, I suddenly have created a Timeline project.
Apparently this project ‘overrules’ the Playlist project, because activating the ‘Project’ tab now results in the ‘Resulting timeline’ showing the timeline of the ‘Timeline’ project (i.c. the timeline of clip 1B). But when I choose ‘Goto’ from the Playlist item’s context menu, the ‘Project’ tab is highlighted, but the ‘Resulting timeline’ shows the timeline of the Playlist project.
Sorry for the long text, but I hope I’ve described the source of my confusion accurately, thus trying to help you to make your wonderful software even better 
If I may finish with some suggestions:
- Add an extra tab next to ‘Source’ and ‘Project’, called ‘Timeline Project’, while at the same time renaming ‘Project’ to ‘Playlist Project’. When activated, the project tabs should show the according timeline in the ‘Resulting timeline’.
- In the Playlist item’s context menu, rename ‘Goto’ to ‘Goto clip in Playlist project’, and rename ‘Open as Clip’ to ‘Goto clip in Source’.
- Maybe add a ‘Goto clip in Timeline project’ or ‘Goto clip in Track’ in the Playlist item’s context menu as well, but this might get tricky if a clip is added multiple times to a Track/Tracks (then probably sub-menus are needed).
Cheers,
Roger