Showing Winforms on dual-screen setup

Question

I have a winforms application in C#, with about 10 forms to navigate through.

On all of them, I have set StartPosition as CenterScreen but I use a laptop with a second screen plugged in.

Now the application starts randomly on one of my screens. Also even if the app is on one screen, MessageBoxes pop up on the second one. How can I set the application to always start at the main screen, the one set as "1" in Windows.

I also want to bind the application to the screen it is showing at so that MessageBoxes would appear on the same screen as the app. Another thing I would like to have is so that new forms would show on the same position as previous forms, not going back to the screen where the application started.

What should I use to control the positions of the forms?

I tried changing StartPosition to CenterParent, but that doesn't seem to change anything.

When you open a MessageBox, are you specifying an IWin32Window parent, or are you calling the versions of Show() that starts with the message text? Because you always want to specify a parent window if you have one, that way it will know where to show the dialog. — Bryce Wagner, Jul 31 '19 at 10:09
If you're calling it from a form or user control, you'll want to call MessageBox.Show(this, "Message") instead. — Bryce Wagner, Jul 31 '19 at 10:15
"I also want to bind the application to the screen it is showing at so that MessageBoxes would appear on the same screen as the app." ... I wish the Gimp team cared enough to do that. — AlwaysLearning, Jul 31 '19 at 10:48

Mohammad Reza Shahrestani · Answer 1 · 2019-07-31T13:02:46.830

2

Try this out on starting page ( first form):

private void MyForm_Load(object sender, EventArgs e)
{
        this.Location = Screen.AllScreens[0].WorkingArea.Location;
        this.StartPosition = FormStartPosition.CenterScreen;
}

More information here : Showing a Windows form on a secondary monitor?

This question is about showing program on secondary screen. just change 1 index to 0 on arrays if you used answers of that.

Edit:

Just for emphasize Bryce Wagner comment for other people read this question :

If you're calling it from a form or user control, you'll want to call MessageBox.Show(this, "Message") instead.

edited Jul 31 '19 at 13:02

answered Jul 31 '19 at 10:08

Mohammad Reza Shahrestani

1,119
3
17
28

You mean I should put this code only in the first form, or in each form? – TK-421 Jul 31 '19 at 10:15
I think this will work for you. use that in MyForm_Load – Mohammad Reza Shahrestani Jul 31 '19 at 10:21
But in which form? Every form, or only the first one? – TK-421 Jul 31 '19 at 10:22
Use it in first form for problem u said Application will start randomly on both screens. – Mohammad Reza Shahrestani Jul 31 '19 at 10:26
@TK-421 if that solved your problem comment or accept so I complete that – Mohammad Reza Shahrestani Jul 31 '19 at 10:33
Your solutions only shows the form on the correct screen, but it no longers open in the center of the screen. – TK-421 Jul 31 '19 at 11:50
@TK-421 use this in load method : this.StartPosition = FormStartPosition.CenterScreen; – Mohammad Reza Shahrestani Jul 31 '19 at 12:53
Let us [continue this discussion in chat](https://chat.stackoverflow.com/rooms/197277/discussion-between-tk-421-and-mohamad-shahrestani). – TK-421 Jul 31 '19 at 13:19

score 1 · Accepted Answer · answered Jul 31 '19 at 13:29

Combining all answers here and in similar questions, the working solution for showing app on primary screen is this:

private void FormLogin_Load(object sender, EventArgs e)
    {
        this.Location = Screen.AllScreens[0].WorkingArea.Location;
        ReallyCenterToScreen();
     }
    protected void ReallyCenterToScreen()
    {
        Screen screen = Screen.FromControl(this);
        Rectangle workingArea = screen.WorkingArea;
        this.Location = new Point()
        {
            X = Math.Max(workingArea.X, workingArea.X + (workingArea.Width - this.Width) / 2),
            Y = Math.Max(workingArea.Y, workingArea.Y + (workingArea.Height - this.Height) / 2)
        };
    }

And to keep the MessageBoxes on the center screen is this:

MessageBox.Show(this, "Message")

Sources are the comment of @Bryce Wagner to my question, the answer from @Mohamad Shahrestani and from this question answer by @Sarsur.A

score 1 · Answer 3 · edited Dec 11 '21 at 14:47

I have a laptop with a second screen. Windows 10 is in "Extend" mode. None of the code examples helped with my dialog ignoring the manual location.

It turns out that NVidia has some helpful options in their driver. One will decide for you where you want your form or your dialog. If your code just doesn't seem to behave, try the "nView Desktop Manager" -> "Windows Manager" -> "Dialog box repositioning" and Open windows on settings.

Showing Winforms on dual-screen setup

3 Answers3