test/tree focus box has artifacts on some linux boxes

[erco77]

Hmm, I know we "solved" the focus box issue in 1.4.x with some kind of changes, but Fl_Tree was not affected, because it's showing those old noisy focus box drawing artifacts again.

It should be noted that Fl_Tree's focus box drawing is handled by the items, Fl_Tree_Item, which has to have its own focus drawing code because it is necessarily does /not/ derive from Fl_Widget, and therefore cannot access Fl_Widget::draw_focus().

Looks like there was a regression in 7a580fd with changes made to Fl_Tree_Item::draw_item_focus() where the workaround for this problem was commented out, causing the issue to reappear.

[erco77]

[erco77]

Fixed result, closing.