[Interest] QTreeView expand icon changes unexpectedly Qt5.6.0 & VS2015

[anton]

Hi,

I installed the following qt version on my Windows 7 (64bit):

http://download.qt.io/official_releases/qt/5.6/5.6.0/qt-opensource-windows-x86-msvc2015_64-5.6.0.exe

I use Visual Studio 2015 update 2.


I create a Qt Widget application with q 
QTreeView and some QComboBox'es.

In my treeview I see the expand iccons:

- they look like a triangle lile '>' when the treenode
  is *not* expanded

- they look like a triangle lile 'V' when the treenode
  is not *expanded*

Now I click here and there in my application,
clicl on a QComboBox and now some strange magic happens.

1. The expand icons change to a '[+]': a plus in a rectangle
   like you know it from the windows explorer.

2. As soon as the mouse pointer hoovers over the 
   expand icon it becomes *insisible*.

In the Qt Designer in Qt Creator, I see the same problem,
the expand icons (in the property pane)  
look like a '[+]' like in the windows explorer,
but they becone invisible as soon as the mouse pointer is over
the expand icon.


My questions:

- do you observe the same things?
- did I forget to initialize something?
  (don't think so because the Qt Designer has the same problem)
- or is it a bug which will be fixed in 5.6.1 or 5.7.0 ?


Thanks for a hint

  Anton