Not wanting to create a rush to the door, and I will go on using OO and OG with pleasure for a number of minor purposes, but for most of my work, I find that I am suddenly using Tree ($15) http://itunes.apple.com/us/app/tree/id451104825?mt=12 where I was previously using OG5s outliner (outlines too small, clumsy and slow) or OO3 (no tree diagrams of my outline).

I have always thought it was a pity that Omni, with its strengths in both outlines and diagrams, didn't integrate or equip OO/OG well enough to support rapid thinking and reorganising in terms of trees. (There's no tree-node collapse and expand in OG5 for example, and there's no graphic view in OO).

A good, clear, highly responsive, and collapsible tree-based editing mode like Tree's Tree view would make OO4 a killer app for me.

Without it, I'll very happily stick to working like this (image in a review by Brett Terpstra):
http://brettterpstra.com/app-review-...er-i-can-love/
I simply find I'm getting much more done by the end of each hour …

The thing is fast and elegant, and simply works …

(No more flipping back and forth between outlines and tree views, and feeling frustrated by not being able to collapse sub-trees in OG, or by the buggy outcomes of its non-orthogonal layouts lying in hiding under orthogonal links – a relief ...)

To translate this into requests for OO4 and OG6 it would simply be something like:

1. A http://www.topoftree.jp/en/tree editing view for OO4
2. The same for OG6 ...

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Oh and another thing – visual layering of information.

One of the things which Tree gets right is graphic design. Full contrast is reserved for the user's data, while technical impedimenta (bullets etc) are pushed back to a quieter visual plane.

OmniOutliner still has unadjustable full-black bullets and disclosure triangles –competing for visual attention with the words.

Another request for OO4: grayed bullets (or at least an option for them).

Tree's simple and unobtrusive bullets and collapsible tree-links can be seen in the attached.

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One of the things which I find brilliant in Kazuhiro Kawana's Tree view (and which OO4 would really need to bring me back) is that it offers mixed modes of expansion in the same view.

Children can either be expanded horizontally in a column to the right of the parent, or vertically, with the traditional slight indents, in the same column.

Thoughtful simplicity, and quite simply better for thinking … (simple outlining, with much clearer visualisation of broad structure – no need for the eye to travel up and down to try to match up equally indented nodes, and the flexibility to save screen space by reverting to the traditional idiom wherever that seems useful). Very clever design ...