The container is not visible, so its size can be pretty much the entire screen. There is no problem with that.
Yes, there is a problem with that. Changing the positioning is unnecessarily more convoluted than it should be. Right now the icons are anchored to the bottom-right of the container. If I wanted them above the unit portrait, I'd have to change the anchoring of the container and the icon template. Also, it interferes with being able to click on other frames in the UI editor.
But, if you really want to, you can set an anchor to a child frame via just using the child frame's name in the anchor's relative="ChildFrame". If you position your last upgrade icon slot properly, you can just use its top border (= "Min").
And what if I later decide to add/rearrange/remove things? Then I have to find and update every other frame that was anchoring to some arbitrary child instead of the container when that was really the intent.
I'm not looking for good 'nuff's. I want to know the proper, clean way.
I understand that. The part that I don't understand is how to apply this to frames containing many different frames, especially frames that aren't tooltips. E.g. I want to wrap up those two number icons (each one made up of a background image, an image and a label) in a container that could then be positioned anywhere easily. Right now I have the container stretching up all the way to $parent (FullscreenUpperContainer) except for the bottom, which is anchored to the top of the command card, because I can't make it only as tall and wide as it needs to be (without hard-coding values).
Sorry for the delay. The thing is I'm not quite happy with the solution I came up with yet. Specifically, I want to make it so you can have nice tooltips (instead of this) on the icons and also allow you to position them more flexibly (right now it's positioned relative to the command card and changing it to, for example, above the minimap would require several XML edits).
But the layout engine in SC2 is hard...
Just to give you an idea, the functionality I'm trying to leverage ("CollapseLayout"), isn't documented anywhere and comes up with a mere two pages of search results on Google. This is a dark magic that very few people understand and are willing to teach...
Anyway, what I showed you can be done quick & dirty through triggers (minus the tooltips). Do you want an example map for that in the meantime or can it wait? Or do you want me to just send you what I have now?
From now on, I'm going to use the phrase Pick and do anytime I need to refer to the action Pick each (whatever) and do actions. Because it just sounds awesome in my head.
A word of caution: the "pick each..." family of actions suffers from a couple of weird bugs that can cause errors for no apparent reason whatsoever. They cannot be relied upon and as such I recommend getting in the habit of using the "for each..." actions instead.