Fixed Multicolumn view filtering item arrangement. This relates to bug 146.

Signed-off-by: Michele Calgaro <michele.calgaro@yahoo.it>
(cherry picked from commit 9655b0b845)

src/iconview/qiconview.cpp

@@ -2342,14 +2342,15 @@ void QIconViewItem::checkRect()
 
     When an item is inserted the QIconView allocates a position for it.
     Existing items are rearranged if autoArrange() is TRUE. The
-    default arrangement is \c LeftToRight -- the QIconView fills up
-    the \e left-most column from top to bottom, then moves one column
-    \e right and fills that from top to bottom and so on. The
+    default arrangement is \c LeftToRight -- the QIconView fills
+    the \e top-most row from left to right, then moves one row \e down
+    and fills that row from left to right and so on. The
     arrangement can be modified with any of the following approaches:
     \list
-    \i Call setArrangement(), e.g. with \c TopToBottom which will fill
-    the \e top-most row from left to right, then moves one row \e down
-    and fills that row from left to right and so on.
+    \i Call setArrangement(), e.g. with \c TopToBottom which will fill up
+    the \e left-most column from top to bottom, then moves one column
+    \e right and fills that from top to bottom and so on.
+    
     \i Construct each QIconViewItem using a constructor which allows
     you to specify which item the new one is to follow.
     \i Call setSorting() or sort() to sort the items.
@@ -6035,7 +6036,7 @@ QIconViewItem *QIconView::makeRowLayout( QIconViewItem *begin, int &y, bool &cha
 	}
 
 
-    } else { // -------------------------------- SOUTH ------------------------------
+    } else { // -------------------------------- TopToBottom ------------------------------
 
 	int x = y;
 
@@ -6070,6 +6071,7 @@ QIconViewItem *QIconView::makeRowLayout( QIconViewItem *begin, int &y, bool &cha
 
 	    // now move the items
 	    item = begin;
+	    QIconViewItem *prevVisibleItem = NULL;
 	    for (;;) {
 		item->dirty = FALSE;
 		if ( d->itemTextPos == Bottom ) {
@@ -6077,15 +6079,16 @@ QIconViewItem *QIconView::makeRowLayout( QIconViewItem *begin, int &y, bool &cha
 			changed = item->move( x + ( w - item->width() ) / 2, d->spacing )  || changed;
 		    else
 			changed = item->move( x + ( w - item->width() ) / 2,
-					      item->prev->y() + item->prev->height() + d->spacing ) || changed;
+					      prevVisibleItem->y() + prevVisibleItem->height() + d->spacing ) || changed;
 		} else {
 		    if ( item == begin )
 			changed = item->move( x, d->spacing ) || changed;
 		    else
-			changed = item->move( x, item->prev->y() + item->prev->height() + d->spacing ) || changed;
+			changed = item->move( x, prevVisibleItem->y() + prevVisibleItem->height() + d->spacing ) || changed;
 		}
 		if ( item == end )
 		    break;
+		prevVisibleItem = item;
 		item = item->next;
 		while (item && (item->isVisible() == FALSE)) {
 		    item = item->next;