Control does not support transparent background colors

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C#

dear my friends , i got this error (Control does not support transparent background colors)
i tried a lot of code at form but same issues , i was think my project have something wrong or missing , but i get empty form and project and i got same issues , so c# stop support BackColor transparent

Note: i make launcher/Patch for online game
i want to make my form as picture png

thanks so much

What I have tried:

i tried :
form.BackColor = Color.Fuchsia;
form.TransparencyKey = form.BackColor;
form.BackgroundImage = Image.FromFile("D:\\pie.png");
form.Paint += form_Paint;
//form.MouseDown += form_MouseDown;
form.Show();

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this.SetStyle(ControlStyles.SupportsTransparentBackColor, true);

InitializeComponent();
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this.BackColor = colorDialog1.Color;

if (colorDialog1.ShowDialog() == DialogResult.OK) {

this.BackColor = colorDialog1.Color;
Util.gs_ThemeColor = colorDialog1.Color.Name;

}



this.BackColor = Color.FromName(Util.gs_ThemeColor);
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this.SetStyle(ControlStyles.SupportsTransparentBackColor, true);
this.BackColor = Color.Transparent;