My Application's Main Form opens on the Laptop (main screen) when it starts. Then user drags it to the other screen (for big display), and opens a child form that is displayed on the Laptop screen rather than Application's Main Form (big display). I want the child form to open on the screen where Application's Main Form is open at the moment.

I tried following options, but they only worked in debug mode and did not work in production

ChildForm.ShowDialog((IWin32Window)this.MainForm);
ChildForm.ShowDialog(formMainInstance);
ChildForm.Show(formMainInstance);

I know about FormStartPosition.CenterParent, but it's not the right option for me. How can I do this?

CodePudding user response：

As far as I know you have 3 options:

1. Use FormStartPosition.CenterScreen;

        private void button2_Click(object sender, EventArgs e)
    {          
        Form2 child = new Form2();
        child.StartPosition = FormStartPosition.CenterScreen;
        child.ShowDialog(this);
    }
   

2. Use FormStartPosition.CenterParent

   private void button2_Click(object sender, EventArgs e)
    {          
        Form2 child = new Form2();
        child.StartPosition = FormStartPosition.CenterParent;
        child.ShowDialog(this);
    }
   

   }

3. Use FormStartPosition.Manual and pass a point

       private void button2_Click(object sender, EventArgs e)
    {          
        Form2 child = new Form2();
        child.StartPosition = FormStartPosition.Manual;
        child.Location = new System.Drawing.Point(0, 0);
        child.ShowDialog(this);
    }
   

CodePudding user response：

The following code worked for me.

var screen = Screen.FromControl(childFormInstance);
var MainFormScreen = Screen.FromControl(_formMainInstance);
ChildForm.Left = MainFormScreen.WorkingArea.Left   120;
ChildForm.Top = MainFormScreen.WorkingArea.Top   120;
ChildForm.ShowDialog();

1. First I query which screen the child form want to open
2. Then I query which screen my Main form is currently open
3. Then I over right the child form screen