Displaying msgbox to close the opened child form.

Question

Hi I m having 12 forms in my application. I want to display a message box asking the user to close the existing opened child form before opening other. I had tried the following the code: Form curfrm; String a =  Please Close the other open windows; private void admissionForm1ToolStripMenuItem_Click(object sender EventArgs e) { adfrm1 af1 = new adfrm1(null); if (curfrm != null) { MessageBox.Show(a); return; } else { curfrm = af1; af1.MdiParent = this; af1.Show(); } This doesn't allow me to open the other forms after closing the child form. Thanks.

Vulpes · Answer

The problem is that when the user closes the ChildForm this won't automatically set curfrm to null. One way you could do that would be to handle the child form's FormClosed event and set it to null from the handler. The code would be something like this: Form curfrm; String a =  Please Close the other open windows; private void admissionForm1ToolStripMenuItem_Click(object sender EventArgs e) { if (curfrm != null) { MessageBox.Show(a); return; } else { curfrm = new adfrm1(null); curfrm.MdiParent = this; curfrm.FormClosed += curfrm_FormClosed; // add handler curfrm.Show(); } } // type this in manually not via the designer private void curfrm_FormClosed(object sender FormClosedEventArgs e) { curfrm = null; curfrm.FormClosed -= curfrm_FormClosed; // remove handler }