PythonWin: WM_GETMINMAXINFO modify LPPOINT doesn't work?

[Robert]

I want to set a minimum tracking size for a dialog, by handling
WM_GETMINMAXINFO.
I managed to overwrite the correct memory location of the MINMAXINFO
structure. I see the right values going really in and out, but it
doesn't take effect like it does in mere MFC code. What could be the
reason?  (Also tried WM_SIZING but also no effect) - Robert

    def WM_GETMINMAXINFO(self,msg):
        print "WM_GETMINMAXINFO", msg
        lp=msg[3]
        ymin=ext.GetMemInt(lp+7*4)   # min tracking size Y  
        ymax=ext.GetMemInt(lp+9*4)   # max tracking size Y
        print "ymin",ymin,ymax
        ext.SetMemInt(lp+7*4,300)
        ymin=ext.GetMemInt(lp+7*4)
        print "ymin",ymin
        return 0  #True