Tree/List commands should only be enabled when they can execute

[jrieken]

The WorkbenchTree in combination with the IListService and its commands bind some keys overly aggressive. For instance, ArrowLeft and ArrowRight always try to collapse/expand elements in a tree even though there is nothing to collapse or Escape tries to clear the selection when there is no selection. The consequence is that those keys cannot be used for other commands when a tree is focused (like the breadcrumbs).

[bpasero]

Maybe one way out is to add more context keys depending on:

• current element can be expanded or not
• there is an element selected in the tree

This would result in quite a bit of context key changes I guess when navigating around the key.

[jrieken]

Yeah, more context keys is always the answer to this and I wouldn't be worries about them changing

[bpasero]

@jrieken I added a listHasSelectionOrFocus context that is only true if the list/tree has a selection or focused item and added it for the list.clear command (ESC).

I don't know why the list never implemented this command properly but I also went ahead and now the list will get its selection or focus cleared when pressing escape key.

[joaomoreno]

What to do here?

[bpasero]

@joaomoreno the tree/list needs to expose some additional APIs so that the WorkbenchTree/List can set some appropriate context keys properly. E.g.:

• is first/last element
• is expanded/collapsed

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[OliverJAsh]

Two other issues have been marked as duplicates of this one: #58318 and #98321. I was also about to file a new issue until I found this. Can we re-open this as it's quite an important one?

Until this is fixed the breadcrumbs are extremely difficult to use for keyboard users. Unfortunately,
the workaround mentioned here is far from sufficient because once the breadcrumbs list is open, there is no way to return focus to the breadcrumb menu.