in bookmarks_key_press_event_cb () we use get_cursor () to open the current item; however, in the same function we use gtk_tree_selection_select_iter () to set it on up/down keypresses. these two calls don't play along: tree cursor != tree selection.

the attached patch fixes this issue by using gtk_tree_model_get_selection () instead.

(I'd rather not use _set_cursor () because AFAICS that would open the selected item when pressing up/down, which is quite annoying when moving through the sidebar with keynav only.)

please review.