fix issue, then it wasn't possible to view FBD programs

the reason for that is possible wx-3.0-gtk2 bug that happens if
ALWAYS_SHOW_SB is set.

Traceback (most recent call last):
File "Beremiz.py", line 1045, in OnProjectTreeItemActivated
IDEFrame.OnProjectTreeItemActivated(self, event)
File "IDEFrame.py", line 1667, in OnProjectTreeItemActivated
self.EditProjectElement(item_infos["type"], item_infos["tagname"])
File "IDEFrame.py", line 1752, in EditProjectElement
new_window = Viewer(self.TabsOpened, tagname, self, self.Controler)
File "editors/Viewer.py", line 611, in __init__
EditorPanel.__init__(self, parent, tagname, window, controler, debug)
File "editors/EditorPanel.py", line 68, in __init__
self._init_ctrls(parent)
File "editors/EditorPanel.py", line 52, in _init_ctrls
self._init_Editor(self)
File "editors/Viewer.py", line 603, in _init_Editor
style=wx.HSCROLL | wx.VSCROLL | wx.ALWAYS_SHOW_SB)
File "/usr/lib/python2.7/dist-packages/wx-3.0-gtk2/wx/_windows.py", line 296, in __init__
_windows_.ScrolledWindow_swiginit(self,_windows_.new_ScrolledWindow(*args, **kwargs))
PyAssertionError: C++ assertion "scrolled" failed at ../src/gtk/scrolwin.cpp(205) in DoShowScrollbars(): window must be created

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IEC 61131-3

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===========

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    IEC-61131 is a normative document provided by the standards organization IEC

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    (International Electrotechnical Commission) and describing a standard for

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    implementing programmable controllers.

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    The part 3 of this document (commonly named IEC 61131-3) specifies syntax and 

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    semantics for programming language for programmable controllers. Beremiz

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    implements all the languages described in this document. 

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    http://www.iec.eu

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PLCopen TC6

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===========

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    PLCopen is a vendor- and product-independent worldwide association defining

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    international standards for various topics related to control programming.

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    For this purpose, PLCopen has 6 technical committees.

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    The goal of the sixth committee (TC6) is to define a standard file format, 

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    based on XML, for exchanging programmables controllers programmed using 

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    IEC 61131-3 languages. Beremiz uses this file format for saving the PLC

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    programs of projects.

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    http://www.plcopen.org

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