Created attachment 6927 
Fixing patch for exo version 0.10.7

=== STEPS TO REPRODUCE ===

1) Go to keyboard settings and choose fastest possible key press repeat speed.

2) Open Thunar in any directory that (and a few parents of that, too) contains more than one element.

3) Select View->View as Icons.

4) Press the "right arrow" key, wait a couple of seconds (at least key press repeat delay) and start clicking "Open the parent folder" button (keeping "right arrow" key holding).

After a few clicks segfault will occur.

=== CAUSE ===

ExoIconView widget may be in inconsistent state where item->n_cells != icon_view->priv->n_cells for some item. In such cases layout_callback with priority G_PRIORITY_DEFAULT_IDLE is scheduled which recalculate item sizes and reallocate memory for item->{box,after,before}, thus making icon_view consistent again.

But X events are scheduled with higher priority G_PRIORITY_DEFAULT, so key press handling may occur when icon_view is still inconsistent. The latter may end up in calling exo_icon_view_scroll_to_item, and, finally, exo_icon_view_get_item_needed_size, which iterates over icon_view->priv->cell_list and indexes item->box by info->position without checking for item->n_cells (which may be less that icon_view->priv->n_cells). This leads to crash.

=== REMEDY ===

Note that another function, exo_icon_view_scroll_to_path, checks for this inconsistency (indicated by icon_view->priv->layout_idle_id != 0 condition) and delays scrolling in this case. Otherwise it calls aforementioned exo_icon_view_scroll_to_item.

The patch (see attachment) fixes the bug (tested against exo-0.10.7).

(It's probably better to pass extra GtkTreePath* parameter (or just its the only index) to not search for index of item in icon_view->priv->items.)