Refactor Panel, Layout, Expo and Scale to handle various panel configurations

[autarkper]

Expo and Scale don't work well with the non-default panel configurations ("classic" and "flipped") and auto-hide, and there are also some other problems when using non-standard panel sizes. This pull request is a large step towards making configurable panels work in a predictable fashion.

See also: #951.

[Cobinja]

@autarkper: could you take another look at this? currently it breaks setting bottom panel height without cinnamon restart. the position is not adjusted (probably to not calling LayoutManager.updateBoxes)

[autarkper]

@Cobinja: The way I see it, it is already broken in master. It is one of the remaining warts, but I don't think I have made it any worse than it already is. Please check again and correct me if I'm wrong.

[Cobinja]

@autarkper: I checked. In master it works fine.
Problem seems to be the deletion of lines 784 and 808 from panel.js

[autarkper]

@Cobinja: Well then I'm doubly stumped, once for not being able to reproduce correct behavior in current master, twice for not being able to fix it on my branch. Re lines 784 and 808, they have not been deleted, but reworked. The call of Main.layoutManager._updateBoxes is done in layout.js instead; duplicating the call in panel.js does not have any perceivable effect.

[Cobinja]

@autarkper: you need to call layoutManager._updateBoxes every time the panel height is changed. otherwise the y-position of the bottom panel is not adjusted.

[autarkper]

If you put a log statement in _updateBoxes you will see that it is called. Please note that the code works for the top panel.

[Cobinja]

@autarkper: I looked again. Your 3rd commit solves it.
Imho it would be better to just call _updateBoxes from panel.js instead of doing all that autohide change stuff in layout.js additionally (inc. avoiding the "interesting" naming scheme with onPanelAutoHideChanged reacting to changes in "panel-top-height" and "panel-bottom-height").

[autarkper]

The latest commit solves the problem with the desktop not resizing correctly after changing the size of the bottom panel.

@Cobinja: There must be something different in our configurations, because I had to do even more to make it work around here. As I've said before, simply calling _updateBoxes from panel.js does not work for me. I agree that the names are not very descriptive anymore; I'll try and find something more suitable.

[Cobinja]

@autarkper: The problem with the desktop size is solved. Still, there's something that's not really a problem. Showing and instantly hiding a panel when changing the height with autohide on looks somehow weird (at least to me).

[autarkper]

@Cobinja: Thanks for testing! Flashing the panel bugs me too, a bit, but given that users probably won't be changing panel settings very often I hope it'll be acceptable. Actually, I think the ability to resize panels currently isn't very useful anyway, since the contents doesn't scale.

[autarkper]

I have squashed the commits somewhat.

[Cobinja]

@autarkper: For "autohide on" i think we don't have to adjust the desktop size, since it's not affected by autohidden panels.

[autarkper]

@Cobinja: Is that really so? Turning auto-hide on should reclaim the space previously occupied by the panels.

[Cobinja]

@autarkper: Sry, that wasn't expressed well. Better: While autohide is turned on, I think we don't have to adjust the desktop size when setting a new panel height, since it's not affected by an autohidden panel, and thus we can maybe avoid showing and instantly hiding the panel.

[autarkper]

@Cobinja: OK, that makes sense. I'll check.

[autarkper]

@Cobinja: I have investigated making an exception when auto-hide is on and not changing, but the result is not satisfactory. I won't have much more time to work on this issue, so I'll have to leave it as it is.

[autarkper]

This will no longer merge cleanly to master; there is currently a conflict in panel.js that cannot be mechanically resolved. Unfortunately I'm not able to work that out for the time being.

[autarkper]

I'm closing this for now, as this needs more testing. I would also like to investigate whether we can support multi-monitor configurations better than today.