Fix potential endless loop in layout

Usecase:
- No scrollbar is shown
- Window size will be decreased so that a scrollbar gets necessary

The decreased window size minus the space required for the scrollbar
results in a relayout of the items. In 99 % of all
cases a decreased window size won't result in showing more items in parallel in
comparison to a larger window size. However in the remaining 1 % this can
happen (e.g. see bug 293318 for a sample). This results in an endless loop as
now no scrollbar is required anymore, the layout changes again, the scrollbar
is required again, ...

BUG: 293318
FIXED-IN: 4.8.1

1 files changed, 7 insertions, 0 deletions

diff --git a/src/kitemviews/kitemlistcontainer.h b/src/kitemviews/kitemlistcontainer.h
index 4d6eadbbb..b41f48a7f 100644
--- a/src/kitemviews/kitemlistcontainer.h
+++ b/src/kitemviews/kitemlistcontainer.h
@@ -70,6 +70,13 @@ private:
     void updateGeometries();
     void updateSmoothScrollers(Qt::Orientation orientation);
 
+    /**
+     * Helper method for updateScrollOffsetScrollBar(). Updates the scrollbar-policy
+     * to Qt::ScrollBarAlwaysOn for cases where turning off the scrollbar might lead
+     * to an endless layout loop (see bug #293318).
+     */
+    void updateScrollOffsetScrollBarPolicy();
+
 private:
     KItemListController* m_controller;