[A11y] AtkRelation's missing between "Folder" label and combo box in New Project Dialog

[Joanmarie]

In Jokosher's New Project Dialog:

1. There should be an AtkRelation of type ATK_RELATION_LABEL_FOR set on the "Folder" label which points to the combo box.

2. There should be an AtkRelation of type ATK_RELATION_LABELLED_BY set on the combo box which points to the "Folder" label.

The primary impact of this bug is that when a user who is blind gives focus to the "Folder" combo box, the user's screen reader has no way of knowing what labels the combo box and therefore cannot present that information to the user.

Note that these relations are present for the Project Name and Author entries, so whatever you did there can probably be done for the combo box.* :-)

*In a fit of laziness, I haven't actually looked to see what was done for the Project Name and Author entries; however, you can usually get the desired, label-related AtkRelation as a side effect of setting the mnemonic widget property for the label.

Docs:
http://library.gnome.org/devel/atk/unstable/AtkRelation.html
http://library.gnome.org/devel/atk/unstable/AtkRelationSet.html