Fix #315779: Disable auto-size of vertical frame when dragging the height handle

[cbjeukendrup]

Resolves: https://musescore.org/en/node/315779

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[Jojo-Schmitz]

There a few mtests that fail, seems those insist on 10 being the height of vertical frames. I don't quite get why and how thios is related to disabling the Autimatic site on dragging that size handle?

[Jojo-Schmitz]

Is this here the cause for the mtest fails?

[jeetee]

Seems likely, as those now all get that default size set explicitly due to auto-size instead of keeping the old size value.

[cbjeukendrup]

I think I have found a way of doing it without this line. I will try that soon.

[MarcSabatella]

That certainly looks a lot safer now. Just thinking it through - what is the expected behavior if you turn autosize off for a box that has been expanded already buy this - should the box snap to the height given in the Inspector? And then let's say you add more content to the box, and now it's not big enough - should turning it on automatically snap the box to the required size? Currently, both happen, and I think that's probably as expected. It looks to me like this change won;t affect that, which is good, but also works as I expect with respect to dragging, where starting a drag on an autosize-expanded box disables autosize but does not cause the box instantly shrink. In that sense it's very much like how Alt+drag of an autoplaced element disables autoplace but doesn't cause the position to suddenly reset.

So on paper all is good as far as I am concerned.

Once thing that has bugged me about the autosize design all along is that magic number 10 sp that basically serves as a minimum box height with autosize enabled. I'd have preferred this to have been a style setting, assuming we could work out the compatibility implications. FWIW, it's technically possible to implement that without much of a UI change, just add the style setting and mark the height property as styled in the boxStyle definition in box.cpp. This should automatically result in a "set as style" button being added to the Inspector. But, I'm not really recommending that right now - something to think about though.

[igorkorsukov]

@cbjeukendrup Could you please port the changes to the master

[cbjeukendrup]

@igorkorsukov Yep, coming soon!