The recent memory management changes caused the wizard windows to have an incorrect layout so that
the wizard pages were not visible. Reperforming a layout of the GUI elements did not help. The
solution is to not initialise sets of max_pages of wx.BoxSizer elements in the wizard __init__()
method, but to generate and append these dynamically via the add_page() method. The change now
means that there are no longer multiple unused wx.BoxSizer instances generated for each wizard
window created.
