Evaluate editor height on every show

[taauntik]

Forum Post

Words from @ExtAnimal:

He’s hiding and showing components in there. So the potential height of the tabs changes. So that max height that is needed to make it NOT change height as tabs are changed will need to be recalculated.

[ExtAnimal]

TabPanel.js needs

    onContentElMutation() {
        // When any content changes, then upon next show, applyAutoHeight must be called again 
        this.$measureHeight = true;
        super.onContentElMutation(...arguments);
    }

[ExtAnimal]

But also what is observed in changeContentElMutationObserver will have to be configurable on the widget.

The TabPanel will need to include childList : true, subtree : true in its MutationObserver so that it gets notifications when anything inside it at any nesting level gets changed.