Why collaps row in tree_view since gtk 2.14.0

[Bernd Demian <Bernd Demian csc-dd de>]

hi,
I have a question to select/unselect in gtk_tree_view since gtk+-2.14.0.
In version 2.12 I select a child in tree_view with mouse button 1 and
whith they key Cntl and mouse button 1 I deselect the child row. Since
2.14 we have the effect, that when i deselect the child row - the node
will collaps. Btw the arrow of the father will paint black when I press
Cntl + mouse button 1!
Can anybody give me a hint what is the reason of this new behavior.
thanks bernd