Integrate the activity overview properly

[hedning]

Should at least support these things:

• [x] Overview should preserve the window order
• [x] Window animations should start and stop with the same actor properties
• [ ] Drag and drop windows within the workspace

[olejorgenb]

Example of how to hook into the overview layout: https://extensions.gnome.org/extension/18/native-window-placement/ -- source

NB: There's some outdated approaches too: https://extensions.gnome.org/extension/318/overview-window-sequence/

[olejorgenb]

Ensure that the "on-mouse-over" highlight/chrome doesn't get out of sync when windows are moved between workspaces: (eg. move the first window in a tiling to another workspace)

This seems to happen because the tiling layout is updated (ensure_viewport) when windows are moved out/in. This moves the windows and as a side effect(?) of how gnome-shell's WindowCloneLayout[1] is implemented the clones in the overview moves too. The chrome (WindowOverlay [1]) isn't directly tied to the clone so it does not move.

Might be considered a bug upstream. The overview doesn't handle that windows change position when it's open.

[1] workspace.js

The following is a quick and dirty fix: (the window layout in the overview still becomes a bit messed up, but the chrome and wndowclone is at least in sync)

Workspace = imports.ui.workspace;
Workspace.WindowCloneLayout.prototype._makeBoxForWindow = function(window) {
    // We need to adjust the position of the actor because of the
    // consequences of invisible borders -- in reality, the texture
    // has an extra set of "padding" around it that we need to trim
    // down.

    // The outer rect (from which we compute the bounding box)
    // paradoxically is the smaller rectangle, containing the positions
    // of the visible frame. The input rect contains everything,
    // including the invisible border padding.
    let inputRect = window.get_buffer_rect();
    let bb = window.get_frame_rect();

    let box = new Clutter.ActorBox();

    box.set_origin(inputRect.x - bb.x,
                   inputRect.y - bb.y);
    box.set_size(inputRect.width, inputRect.height);

    return box;
}