wxMac: Modal dialog in main frame constructor

[Derek Lee-Wo]

I have an app that displays a modal dialog in the constructor of the
main frame.  This works fine in wxMSW and wxGTK, but in wxMAC it acts
very strange.

The model dialog gets displayed, but then another window pops up.  It
looks like a wxMessageBox in that is the size looks about the same,
but it is blank.  Also, the cursor changes to a spinning wheel, but
just for my app...that is, it's only spinning when I hover over the
modal dialog or the window that popped up?

My modal dialog is not responsive nor is the message box that pops up.

If I bypass this modal and launch it via a menu option, it all works
fine so I have to assume that launching it from the constructor is the
problem.  Is it that this is not allowed on wxMAC, or is there some
magic call I need to make for it to work?

Thanks
Derek