Problem with icon on creating new maximized MDI child form in .NET

Question

I have a .NET 3.5 MDI WinForms application.

I set a a child form's Icon property, and the icon shows up correctly in the top left corner of the form. I then maximize the child form and the icon is still OK.

With the child form still maximized, I open another child window, which automatically comes up maximized. This form's icon is not the one in the Icon property, but the default .NET icon (the one with the blue, red, and yellow squares). However, if I resize the MDI parent form, the icon resets itself and displays properly.

Does anyone have a workaround or know why this happens?

Have you tried doing a .Refresh on the child window after opening it? — Very Very Cherry, Jun 03 '09 at 23:08

score 12 · Answer 1 · answered Jul 15 '11 at 00:26

12

A slight modification to Calanus' solution:

    private void MdiBase_Load(object sender, EventArgs e)
    {
        // Fixes bug where loading form maximised in MDI window shows incorrect icon.
        this.Icon = Icon.Clone() as Icon;
    }

This allows you to set the icon at design time (just as you would for other forms), and does not need any hard-coded file or resource accessing.

answered Jul 15 '11 at 00:26

Tom

326
3
8

For me, this worked when adding the code in the MDI child's form; whereas the example suggests putting the code in the MDI parent's form. – etri Feb 17 '22 at 16:29

score 9 · Accepted Answer · answered Jun 28 '09 at 16:48

Right I have found a solution...

The workaround for this is to set the icon again on the load event of the child form as follows:

private void StatsForm_Load(object sender, EventArgs e)
{
    //bug that means you have to set the desired icon again otherwise it reverts to default when child form is maximised
    Icon = new System.Drawing.Icon("research.ico");
}

This does mean that you will have to first add the icon file in question into your VS project/solution and set it to "Copy Always" so that is copied when your solution is built.

HTH Calanus

Works like a charm. Thanks. For whatever reason I never thought to try resetting the icon. It also works as an embedded resource, so you don't have a ton of (replaceable) files sitting in the final directory. — lc., Jun 30 '09 at 00:33

score 4 · Answer 3 · answered Sep 21 '09 at 10:34

4

I found that the only solution was to deactivate and then reactivate the MDI child:

document.Show();
// Work-around for error in WinForms that causes MDI children to be loaded with the default .NET icon when opened maximised.
ActivateMdiChild(null);
ActivateMdiChild(document);

This is the solution given in this reply on MSDN forums and it worked for me.

answered Sep 21 '09 at 10:34

open-collar

1,404
1
16
22

It works, but creates a problem if you use ShowDialog anywhere. – Drake Sep 30 '10 at 13:40
If you use ShowDialog instead of Show in your code, execution blocks on that call. Only once the dialog is closed do the calls to ActivateMdiChild run, but the second one won't work because `document` no longer exists at that point – alldayremix Jul 12 '13 at 16:41

score 3 · Answer 4 · edited Aug 09 '12 at 00:41

3

private void frmChild_Shown(object sender, EventArgs e)
{
    // Work-around for maximized BUG
    this.Icon = this.MdiParent.Icon;
    this.WindowState = FormWindowState.Normal;
    this.WindowState = FormWindowState.Maximized;
}

edited Aug 09 '12 at 00:41

Christoffer Lette

14,346
7
50
58

answered Jul 03 '11 at 10:05

RickNL

31
1

score 2 · Answer 5 · answered Nov 14 '12 at 04:25

2

Adding this as the first line in the Form_Load method on the MDI Children works for me:

this.Icon = new Icon(this.Icon, this.Icon.Size);

answered Nov 14 '12 at 04:25

Dave Lucre

1,105
1
14
16

score 2 · Answer 6 · edited Jan 02 '12 at 00:46

2

I found out this will fix the problem as well.

myForm.WindowState = FormWindowState.Normal;
myForm.Show();
myForm.WindowState = FormWindowState.Maximized;

edited Jan 02 '12 at 00:46

answered Jul 19 '11 at 08:31

VisserP

21
1

score 1 · Answer 7 · answered May 03 '10 at 19:01

1

My solution: Leave the MdiChild "ShowIcon" property set to true, assign a 1x1 transparent icon. Problem solved.

answered May 03 '10 at 19:01

Jose Wales

11
1

1

Maybe I'm missing something, but I'm not sure how this applies to my original question. The problem is not that an icon shows when I don't want one, but rather that the *icon I want to show* doesn't show and is instead replaced by the default. – lc. May 13 '10 at 05:55

score 1 · Answer 8 · edited Aug 27 '11 at 08:00

1

form.WindowState = FormWindowState.Normal
form.Show()
form.WindowState = FormWindowState.Maximized
form.Show()

Solved my problem!

edited Aug 27 '11 at 08:00

Jérôme Verstrynge

57,710
92
283
453

answered Oct 01 '10 at 20:21

jesus

11
1

score 0 · Answer 9 · answered Sep 30 '10 at 13:48

The best workaround that I found to fix this issue is here.

aNewForm.FormBorderStyle = Windows.Forms.FormBorderStyle.FixedDialog
AddHandler aNewForm.SizeChanged, AddressOf Form_SizeChanged

aNewForm.Show()
aNewForm.WindowState = FormWindowState.Maximized

RemoveHandler aNewForm.SizeChanged, AddressOf Form_SizeChanged

the handler

Protected Sub Form_SizeChanged(ByVal sender As Object, ByVal e As EventArgs)

    If WindowState = FormWindowState.Maximized Then
        If FormBorderStyle <> FormBorderStyle.Sizable Then FormBorderStyle = FormBorderStyle.Sizable
    End If

End Sub

Problem with icon on creating new maximized MDI child form in .NET

9 Answers9

Linked