> Hi Roger,
I try this in VB .NET, it works great!
Appreciate for your help!

Raymond



Raymond:

> 1.  In your MDIParent form, place the following code:

>     private bool _allowChildrenToClose = false;

>     internal bool AllowChildrenToClose
 >    {
 >      get {return this._allowChildrenToClose;}
 >    }

>     protected override void WndProc(ref System.Windows.Forms.Message m)
 >    {
 >      const int WM_CLOSE = 0x10;

>       if (m.Msg == WM_CLOSE)
 >        this._allowChildrenToClose = true;

>       base.WndProc(ref m);
 >    }

> 2.  In your MDIChild form, place the following code:

>     protected override void OnClosing(
 >        System.ComponentModel.CancelEventArgs e)
 >    {
 >      if (((ParentForm) this.MdiParent).AllowChildrenToClose == false)
 >        e.Cancel = true;

>       base.OnClosing(e);
 >    }

> 3.  You will have to change one word in step #2 above.  I use a cast
 >    on the "IF" instruction line to cast "this.MdiParent" to an object
 >    of type "ParentForm".

>     You should substitute whatever type of form your MDIParent form
 >    is for the cast "ParentForm".  So, for instance, if your MDIParent
 >    form is of type MyMdiParentFormClass, then the line should be
 >    changed to the following:

>         if (((MyMdiParentFormClass) this.MdiParent).AllowChildrenToClose
 >            == false)

> The above code (step #1) will trap the WM_CLOSE event in your MDIParent
f> orm.  This event could be raised by:

>   - Clicking the X button in the top-right corner of your parent form.
 >  - Calling the Close() method on your parent form.
 >  - etc.

> In short, it is called whenever someone tries to close the parent form
b> y any means.

> The code in step #2 is called whenever anyone tries to close a child
f> orm.  It first checks to see whether or not the child is closing due
t> o the parent being closed.

>   - If the child is closing because someone clicked the X button in
 >    the upper right corner of the child form, then the child form
 >    will remain open.

>   - If on the other hand, the child is closing because someone is
 >    trying to close the MDI parent form, then the child form will close.

> Cheers.

> - Roger Nedel

>   Nedel Software Solutions
 >  rnedel@n...