[VZ]

Best size is determined by each window. Min size is best size by default, but can be set to something different to override it. And the initial size is also min size by default, because this is what you'd expect: if you create a text entry wide enough for 50 characters, you don't want it to shrink to its best size which would be smaller. Generally speaking, it's best to avoid hardcoding any sizers (and definitely never use sizes in pixels).

For the relayout, the general principle is that it _always_ flows from top to bottom, i.e. changing anything for a child will _never_ affect the size of a (grand) parent. So you just need to call Layout() on the top-most window whose size you want to allow changing. Again, this might be too simple, perhaps, but at least it is simple and 100% consistent (well, wxCollapsiblePane just might be one of the very few exceptions...). I'm not sure how does Qt manage to avoid confusion if it propagates layout changes in both directions.

For markup, we do support it in wxGenericStaticText and several other controls, including buttons, checkboxes and wxDataViewCtrl which is quite enough for simple things like this. wxHtmlWindow is pretty nice for slightly more complicated stuff, even though it's just HTML 3.