toolstrip containing a list of mdi children

Ryoga Makenshi

Hi all,

I'm working on a project with a big number of forms. I'm using an MDI container as my main screen, with a menu and everything, so I can open MDI childs in it.

I inserted a Toolstrip docked at the bottom of the mdi parent, because I had this great idea to show all open mdi children in this toolstrip. Each childform would have it's own ToolStripButton, and the child form which is activated at that time, would be highlighted in the toolstrip. This way, users can see which childs are opened and switch between child forms without having to open the 'window' menu (the one on MdiWindowListItem). I can easily iterate through the MdiChildren list, get some properties, and create the buttons.

So, I started building the code to set this up, but then I hit some problems already. I want the toolstrip to update itself as soon as forms are opened or closed.

- My first idea was to use the MdiChildActivate event on the mdi parent, and build the toolstrip from here everytime it's fired. It's fired whenever an mdi is activated, or closed. Although this almost sounds exactly what I need, I don't want to rebuild it whenever a user switches between two child forms (still fires because of 'activated'). Also, when a child form is closed, the event is fired before it's removed from the MdiChildren list, so it doesn't remove my toolstripbutton at all until it fires again.

- I thought using my own functions would suffice. I created an AddChild(Form child) function, inserted a random number into child.Tag, added an event on FormClosed, and created a ToolStripButton with the same tag. When the child form would close, it would fire the FormClosed event, and then I could easily find the right ToolStripButton with the tag. It was anything but easy, and it still doesn't work. Also, I don't think this is the way to go, because I have tons of child forms, which can create other child forms as well, which need their own functions (+ formclosed event) added as well. I think this is a bit too much for something this simple.

Isn't there a better way to check if child forms are opened or closed from the MdiParent? Something like MdiChildrenListChanged or anything like it?

3 Replies

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sudhir goyal13y ago
thanks a lot.

it is working perfectly.

help me a lot
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Sam Hobbs14y ago
MDi is designed for multiple documents and a window for each document. MDI was not designed as a general-purpose solution for multiple client windows. Beginners often use MDI because it appears to be an easy solution, but then I see questions such as this when problems with MDI are encountered.

Unfortunately I am not sure what a better solution is. The Windows Forms classes seem to be inadequate in this area. I agree that it is strange that Microsoft does not provide more support in that area. The Windows API has solutions that are not available using Windows Forms.
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Ryoga Makenshi14y ago
After some hours of trial and error, I managed to succeed myself, using some code snippet I found elsewhere on the internet and adding some functionality.

In case someone else is searching for this functionality in the future, here are the essential parts of my code, having tlsIDs as my toolstrip. In different places, I'm checking if the items are Toolstripbuttons, because I have labels there as well.

        private List
ChildFormList = new List();
        private void frmMainScreen_MdiChildActivate(object sender, EventArgs e)
        {
            Form f = this.ActiveMdiChild;

            if (f == null)
            {
                //the last child form was just closed
                return;
            }
            if (!ChildFormList.Contains(f))
            {
                //a new child form was created
                Random random = new Random();
                f.Tag = random.Next(1000000);
                ChildFormList.Add(f);
                CreateMDIbuttons();
                f.FormClosed += new FormClosedEventHandler(ChildFormClosed);
            }
            else
            {
                //activated existing form
                foreach (ToolStripItem tsi in tlsIDs.Items)
                {
                    if (tsi.GetType() == typeof(ToolStripButton))
                    {
                        ToolStripButton tsb = (ToolStripButton)tsi;
                        if (f.Tag == tsb.Tag) tsb.Checked = true;
                        else tsb.Checked = false;
                    }
                }
            }
        }
        private void ChildFormClosed(object sender, FormClosedEventArgs e)
        {
            //a child form was closed
            Form f = (Form)sender;
            ChildFormList.Remove(f);
            CreateMDIbuttons();
        }
        private void CreateMDIbuttons()
        {
            for (int i = tlsIDs.Items.Count; i > 0; i--)
            {
                ToolStripItem tsi = tlsIDs.Items[i-1];
                if (tsi.GetType() == typeof(ToolStripButton))
                {
                    tlsIDs.Items.Remove(tsi);
                }
            }
            foreach (Form child in ChildFormList)
            {
                ToolStripButton tsb = new ToolStripButton();
                tsb.Tag = child.Tag;
                tsb.Text = child.Text;
                tsb.BackColor = child.BackColor;
                tsb.Click += new System.EventHandler(toolStripButton_Click);
                tlsIDs.Items.Add(tsb);
            }
            //focus on form
            Form f = this.ActiveMdiChild;
            if (f != null)
            foreach (ToolStripItem tsi in tlsIDs.Items)
            {
                if (tsi.GetType() == typeof(ToolStripButton))
                {
                    ToolStripButton tsb = (ToolStripButton)tsi;
                    if (f.Tag == tsb.Tag) tsb.Checked = true;
                    else tsb.Checked = false;
                }
            }
        }
        private void toolStripButton_Click(object sender, EventArgs e)
        {
            ToolStripButton tsb = (ToolStripButton)sender;
            foreach (Form child in ChildFormList)
            {
                if (child.Tag == tsb.Tag) child.Focus();
            }
        }
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