Going Give You Form Coding.
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Windows Minimize Button.
Code:
WindowState = FormWindowState.Minimized
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Own Form Style.
Make The Background Black and TransparencyKey Black Also.
Then Add Rectangle Shape
Properties:
FillColor: Color You Like
BorderWidth: 10
CornerRaduis: 10
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Photos:


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Now you'r done and you made now you'r own Form Style.
Thanks =)