Comment 4 for bug 837545

I might just comment on the various sections of the code that's changed in order to bring this to place and add a few rationales as to why we're doing this:

WHY WE'RE DOING THIS:
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Partial implementations of what we want from the workspace switcher are already implemented in Unity-2D, such as the layout algorithm that it uses. In Unity-3D we're using the upstream Expo plugin for compiz which hasn't been given all that much attention lately, and it being used as a drop in replacement for what we actually want. Thankfully, the expo plugin is fairly easy to change and we can adapt what was given to us by upstream into something closer to the actual design downstream.

WHAT HAS CHANGED
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This branch changes the following things:
 * Inactive viewports have a dot-pattern displayed above them and are faded out and desaturated (30~ line change)
 * The selected viewport has a glow around it (imported logic from this from the group plugin, which has been well tested) (Add 300~ lines)
 * Click drag uses the XC_fleur cursor to have a "hand" dragging the window rather than an arrow. (4 line change)
 * Added X offset and Y offset options for the layout (20~ lines)
 * Changed option defaults

CONTINGENCY PLAN
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All of these things are implemented as options, if distro doesn't want them, you can turn the option down to its minimum value and there will be no change evident

DOCUMENTATION
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There is no change in behaviour, the only change that will be needed to make to documentation is that the selected viewport now has a glow around it instead of being not darkened and desaturated and screenshots will need to be updated