As it looks for now: The Breadcrumb will stay in the Java Editor for 3.4. In 3.5 we will try to move it out to the trim, this might be a trim kind of thing in the editor area or the workbench trim, but this of course depends on the 3.5 planing and the priorities in 3.5 (think Java 7).

1: The thing I like most about the breadcrumb is that it needs much less space on the screen then the PE. Yes, Mylyn makes the mouse navigation much quicker in the PE. But it does not make the PE smaller. Regarding Alt+click: I don’t know how this works, is this in the PE?

2: If we move it out in 3.5 we would of course be interested in working together with you to get the requirements right. That been said, I’m not 100% convinced that your task switching breadcrumb is really a breadcrumb. The breadcrumb shows the path to the current active element. The active element is the element at the cursor position (or maybe in the future the selected element in a view). Your breadcrumb shows the current active task, if I understand correct, and this is independent of any selection/cursor position. It’s therefore more like an enhanced drop-down, and I’m not sure if we can/should bring this two concepts together. But maybe we can find a common abstraction.

1) For the significant number of developers using Mylyn, Eclipse doesn’t look much like the screenshot above. Instead we see a concise view of only the relevant paths within the containment hierarchy, making mouse navigation to these elements quick. The breadcrumb UI overlaps with the Alt+click mechanism (and keyboard equivalent) that we have for showing all elements under a given project, folder, or type. I haven’t used it enough yet to know, but the editor breadcrumb could be a good alternate way of doing this in case its faster for some use cases.
http://www.eclipse.org/mylyn/images/mylyn-2.0.png
http://live.eclipse.org/node/412

2) Since the Europa we already have an instance of a view that has a breadcrumb trail which is unrelated to editor navigation in the EPP packagings, i.e. Mylyn’s Task List. I think that both consistency and an interaction design that makes room for additional breadcrumb UIs is important. For example, for developers using the Task List’s working set and task switching, this bread-crumb drives which projects are visible and which editors and elements open, and as such feels more primary. For those users moving this to trim could could cause a usability problem. In addition, Mylyn has been trying to put the Task List breadcrumb switcher on the trim for the better part of a year now and we have had experimental support for it for quite some time. It has turned out to be so tricky given the already overcrowded trim and toolbars that we might end up making this vertical trim for Mylyn 3.0 / Ganymede.
http://www.eclipse.org/mylyn/new/images/2.0/working-sets-switch.gif
144161: [patch] Use trim bar to show currently active task
https://bugs.eclipse.org/bugs/show_bug.cgi?id=144161