Code review comment for lp:~rafalcieslak256/millenniumduel/containers

My idea is that one may wish to insert a widget *between* some that already exist. This might be done using a vector too, but inserting items there may look more tricky, as the indexes might change in the meantime. The solution I implemented binds a (potentially) number to each item, so that one can freely insert the items wherever wanted.

Also please note that the struct BoxEntry would still be needed, as it also keeps info about the current size of the widget, the Drawables themselves do not store it, and it has to be recalculated from time to time to ensure proper widget resizing.