> `Button[expand = false]:`
This certainly looks better than a pragma, it would however prevent me from
supporting generic widgets in the future. Especially since the syntax also
needs to support choosing an "adder" (a proc which adds the widget as a child
to the parent), so `HeaderBar[add_titlebar]` would also have to be valid syntax.
> `Button(expand = false):`
Looks better, but would break backwards compatibility, since widget
constructors such as `Label(text = ...)` are currently equivalent to `Label:
text = "..."`. However `expand` is not an attribute of `Button` (and it should
not be, since `expand` only makes sense when a button is added to a `Box`). One
option might be to add a second argument list like `Button()(expand = false):
...`, but I do not think that this looks particularly great.
Here is an idea, which would support adders, but abuses Nim's syntax a bit.
Box:
Button as (expand = false):
icon = "..."
...
Run
Window:
HeaderBar as add_titlebar:
...
Run
Maybe the `add_` could also be either (a) automatically inferred or (b) just
dropped from the procedure names, so the second example becomes: `HeaderBar as
titlebar`.
