Jeremypw/gtk4 prep/bookmark list box cleanup

[jeremypw]

Use equivalent code that will work in Gtk4 as well as Gtk3 as far as possible

[danirabbit]

Just a tiny comment/question/nitpick otherwise this LGTM

[danirabbit]

You start the index at 0 but then immediately make it 1 here. That seems a bit overcomplicated? Why not just start the index where you need it to start? 😅 Also does the row index start at 1? Do we not start at 0?

[jeremypw]

Unless I'm mistaken, when ++ is post-fixed it operates after the variable is used so the current code is equivalent to

Gtk.ListBoxRow? row = list_box.get_row_at_index (index);
index = index + 1;

(when the operator is pre-fixed it increments the variable before using it)

I'll double-check though and see if there is a clearer, equally concise way.

[jeremypw]

@danirabbit
From Vala doumentation:

Increment and decrement operations with implicit assignment. These take just one argument, which must be an identifier of a simple data type. The value will be changed and assigned back to the identifier. These operators may be placed in either prefix or postfix positions - with the former the evaluated value of the statement will be the newly calculated value, with the latter the original value is returned.

So with the postfix operator the lookup expression uses the original (pre-incremented) value as I expected.

[jeremypw]

Now used the pre-fix operator which requires the same number of lines and is clearer. Not sure why I used the post-fix tbh