Fix problem with decreasing size of StatusToolBar when tools are removed from toolbar.

StatusToolBar - toolbar with tool to build, clear, connect, ...
This problem appears only in python-wxgtk3.0. In python-wxgtk2.8 there
was not such problem.

If call StatusToolBar.SetMinSize(wx.DefaultSize), all is working, but
following warning message appears:

(Beremiz.py:15155): Gtk-WARNING **: 18:42:24.115: Negative content
width -6 (allocation 1, extents 4x3) while allocating gadget (node
toolbar, owner GtkToolbar)

To avoid that StatusToolBar.GetToolBitmapSize() is used instead of wx.DefaultSize

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