make clipboard open minimal time as wxPython documentation recommends

https://wxpython.org/Phoenix/docs/html/wx.Clipboard.html#wx.Clipboard.GetData

"Call wx.Clipboard.Open to get ownership of the clipboard. If this
operation returns True, you now own the clipboard. Call
wx.Clipboard.SetData to put data on the clipboard, or
wx.Clipboard.GetData to retrieve data from the clipboard. Call
wx.Clipboard.Close to close the clipboard and relinquish ownership.
You should keep the clipboard open only momentarily."

Maybe it makes situation with pretty annoying error 'clipboard already
open' a little bit better.

traceback:
File "/home/developer/WorkData/PLC/beremiz/avangard-beremiz-ide/src/../../beremiz/BeremizIDE.py", line 955, in OnSaveProjectMenu
self.RefreshAfterSave()
File "/home/developer/WorkData/PLC/beremiz/avangard-beremiz-ide/src/../../beremiz/BeremizIDE.py", line 946, in RefreshAfterSave
self._Refresh(TITLE, FILEMENU, EDITMENU, PAGETITLES)
File "/home/developer/WorkData/PLC/beremiz/avangard-beremiz-ide/src/../../beremiz/IDEFrame.py", line 926, in _Refresh
self.RefreshFunctions[element]()
File "/home/developer/WorkData/PLC/beremiz/avangard-beremiz-ide/src/../../beremiz/BeremizIDE.py", line 766, in RefreshEditMenu
IDEFrame.RefreshEditMenu(self)
File "/home/developer/WorkData/PLC/beremiz/avangard-beremiz-ide/src/../../beremiz/IDEFrame.py", line 1185, in RefreshEditMenu
if self.GetCopyBuffer() is not None:
File "/home/developer/WorkData/PLC/beremiz/avangard-beremiz-ide/src/../../beremiz/IDEFrame.py", line 956, in GetCopyBuffer
if wx.TheClipboard.Open():
File "/usr/lib/python2.7/dist-packages/wx-3.0-gtk3/wx/_misc.py", line 5793, in Open
return _misc_.Clipboard_Open(*args, **kwargs)
<class 'wx._core.PyAssertionError'>: C++ assertion "!m_open" failed at ../src/gtk/clipbrd.cpp(598) in Open(): clipboard already open

     1

// import Nevow.Athena

     2

// import Divmod.Base

     3

     4

function updateAttr(id, param, value) {

     5

  Nevow.Athena.Widget.fromAthenaID(1).callRemote('HMIexec', 'setattr', id, param, value);

     6

}

     7

     8

var svguiWidgets = new Array();

     9

    10

var currentObject = null;

    11

function setCurrentObject(obj) {

    12

	currentObject = obj;

    13

}

    14

function isCurrentObject(obj) {

    15

	return currentObject == obj;

    16

}

    17

    18

function getSVGElementById(id) {

    19

	return document.getElementById(id);

    20

}

    21

    22

function blockSVGElementDrag(element) {

    23

	element.addEventListener("draggesture", function(event){event.stopPropagation()}, true);

    24

}

    25

    26

LiveSVGPage.LiveSVGWidget = Nevow.Athena.Widget.subclass('LiveSVGPage.LiveSVGWidget');

    27

LiveSVGPage.LiveSVGWidget.methods(

    28

    29

    function handleEvent(self, evt) {

    30

        if (currentObject != null) {

    31

            currentObject.handleEvent(evt);

    32

        }

    33

    },

    34

    35

    function receiveData(self, data){

    36

        dataReceived = json_parse(data);

    37

        gadget = svguiWidgets[dataReceived.id]

    38

        if (gadget) {

    39

        	gadget.updateValues(json_parse(dataReceived.kwargs));

    40

        }

    41

        //console.log("OBJET : " + dataReceived.back_id + " STATE : " + newState);

    42

    },

    43

    44

    function init(self, arg1){

    45

        //console.log("Object received : " + arg1);

    46

        for (ind in arg1) {

    47

            gad = json_parse(arg1[ind]);

    48

            args = json_parse(gad.kwargs);

    49

            gadget = new svguilib[gad.__class__](self, gad.id, args);

    50

            svguiWidgets[gadget.id]=gadget;

    51

            //console.log('GADGET :' + gadget);

    52

        }

    53

        var elements = document.getElementsByTagName("svg");

    54

        for (var i = 0; i < elements.length; i++) {

    55

        	elements[i].addEventListener("mouseup", self, false);

    56

        }

    57

        //console.log("SVGUIWIDGETS : " + svguiWidgets);

    58

    }

    59

);