Cannot Move a child Form to a specific location

Lam Thai

Hello,

Here are two lines of code that I'm using to locate a child form, PrefDefPanel, to a specific location:

PreDefPanel.DesktopLocation = new Point(50, 25);
PreDefPanel.Show();

However, this does not work. Before the call to the Show(), debugged values of X and Y for PreDefPanel are 50 and 25, respectively. After the first call to Show(), those values were randomly set. For its subsequent calls, they both increment by 25 pixels! After awhile, they go back to their original values and then the form moves downward diagonally again!

What must I do to fix this problem?

Thanks,
LT

3 Replies

Know the answer? Post it — somebody with the same question will find it here.

Vulpes15y ago
Accepted answer
It's possible to control the position of a form before it's shown by setting its StartPosition property to Manual (the default is WindowsDefaultLocation) and then setting the Location property to what you want:

Form2 f2 = new Form2();
f2.StartPosition = FormStartPosition.Manual;
f2.Location = new Point(0, 0); // display with top left hand corner at origin
f2.Show();

Other settings include CenterScreen and CenterParent.
Lam Thai15y ago
Thank you for your reply. Zoran's answer also works. I used yours.

All the best,
LT
Zoran Horvat15y ago
Windows are ignoring this property when set before showing the form, but rather use their own logic to position child forms.

Solution is to move the form after Windows determine its location, and here is the code sample which demonstrates that:
private void button_Click(object sender, EventArgs e)
{

    Form frm = new Form();
    frm.DesktopLocation = new System.Drawing.Point(100, 150);   // This has no effect
    frm.Shown += new EventHandler(frm_Shown);
    frm.ShowDialog();

    return;
}

void frm_Shown(object sender, EventArgs e)
{
    Form frm = (Form)sender;
    frm.DesktopLocation = new System.Drawing.Point(300, 400);
}

Setting coordinates to (100, 15) has no effect. Only when frm_Shown event handler is added, coordinates (300, 400) set within it will take effect.

Zoran