unity8 surfaces that have never before been in windowed mode should cascade

[kevin gunn]

when launching transitioning to windowed mode or launching applications in windowed mode, each window by default is the same size and locates to the same default location. would be nicer to cascade

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Desired resolution:

- Window/Surface state should be remembered so that if a user switches from windowed mode to staged mode, when the user then switches back to windowed mode the windows should be restored to their previous windowed mode sizes and positions.

- This also applies to staged mode e.g. if a surface was in the sidestage, when the user switches back to staged mode the surface should still be in the side stage.

[John Lea (johnlea)]

@lukas-kde @saviq I've updated the bug description to clarify this change, but I've got a question about the original description - what exactly was meant by 'cascade'? If this is what I think it means e.g. display the windows in a diagonal stack then this is not the desired behavior. We should restore all windows to as close to their original sizes and positions when switching back to windowed mode.

When a user switches back to windowed mode on a different size/resolution display (as is very possible in the convergence case), then we should follow the logic described in the MIR spec for how the windows sizes and positions are modified as minimally as possible to fit onto the new screen size. See the section titled "When a display shrinks, rotates, or is removed" in spec https://docs.google.com/document/d/1L85DdfDd3lDbvchYbgQ45C_lJ1IeTMG4uc7Nuq_XdAE/edit#heading=h.lo6wjg7251og (private document).

[kevin gunn (kgunn72)]

@johnlea the question is not about remembering - and we currently already do that.
the question is, if you enter windowed mode, and you do not have any former window positions stored for any applications, e.g. it's the first time you're opening them. What would be the default location of windows in that case? today with no previous or pre-seeded info they stack directly on top of one another, which feels wrong.

[John Lea (johnlea)]

@kgunn72 ahh, that makes sense, from reading the original issue description I didn't get that this bug was *only* dealing with the issue of entering windowed mode for the first time when windows don't yet have a previous size/position. Yes, in this case the window positions should be cascaded, and the window size should be the default size requested by the application (if available) and if not available a standard size of our choosing.

I'll update the issue description, thanks!

[John Lea (johnlea)]

@kgunn72 description updated