Sorry no code as I deleted the whole thing in frustration. I will recode and
post later. For now it is like following:

Create form with WindowState = Mezimized in design time settings
Open form (with some kind of debugging field, I used variables to get the
state in Location changed and Size changed event)
Form will open mazimized
Click on the min/max button on the form
Form reduce to design time size
Read the value for windowstate and it says maximized.

Thanks.