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