Function getFillEmptySpaceInfo

Finds a frame to fill the empty space left behind by a moved/empty frame (e.g. a dragged frame's original position).

Returns a LayoutChange with the information necessary information..

Changes can be applied to a window with applyFrameChanges.

Examples where * would be the empty space:

Selection priority:

1. Prefer frames listed in preferredFrames (for dragging these are the dragged and target frames). ┌─────┬─────┐ │A │* │ ├─────┼─────┤ │C │B │ └─────┴─────┘

Without preferredFrames set to B, A would be preferred as it shares the shortest edge with the empty space.

┌─────┬─────┐ │A │B │ ├─────┤ │ │C │ │ └─────┴─────┘

In a more complex example:

┌─────┬─────┬─────┐ │A │* │C │ │ │ ├─────┤ │ │ │D │ └─────┴─────┴─────┘

If preferredFrames is C OR D (usually it's both but it might only be one, just take all other frames along that edge if they end at the empty frames end).

┌─────┬──────────┐ │A │C │ │ ├──────────┤ │ │D │ └─────┴──────────┘

And then in the following we would not be able to even expand C or D so we would not be able to satisfy the preference:

┌─────┬─────┬─────┐ │A │* │C │ │ │ ├─────┤ │ │ │ │ │ ├─────┤D │ │ │B │ │ └─────┴─────┴─────┘

2. Prefer the shortest frame that shares an exact edge. Taking the previous example it would be B:

┌─────┬─────┬─────┐ │A │B │C │ │ │ ├─────┤ │ │ │ │ │ │ │D │ │ │ │ │ └─────┴─────┴─────┘