How to prevent multiple child forms opening

**Cor Ligthert [MVP]** · Mar 11 '07, 06:55 AM

Re: How to prevent multiple child forms opening

Tony,

I think that you are searching for the Isdisposed method from a control (and
therefore a form).
http://msdn.microsoft.com/library/de...posedtopic.asp

Cor

"Tony K" <king-tony2@NOSPAMcom cast.netschreef in bericht
news:4D5FB25A-BB34-49F8-B13F-6F6816B1338F@mi crosoft.com...

>I have a MDI application. On the menu toolstrip child forms are selected
>from one of the menus. I don't want to play the disable/enable menu item
>game. I have selected that open forms are added to the "Window" menu item.
>What I'm looking for is when the user clicks on the menu item to open the
>form, how can I check to see if it's open already and if so then set the
>focus (if possible).
>
What happens now is if the menu item is clicked on 2, 3 or even 4 times,
it opens new instances of the form each time.
>
What can I change in this code that opens my child forms to prevent it
from opening new instances?
>
Dim frmCustomers As New Customers()
frmCustomers.Md iParent = Me
frmCustomers.Wi ndowState = FormWindowState .Maximized
frmCustomers.Sh ow()
>
>
Thanks,
Tony

**Heikki Leivo** · Mar 11 '07, 03:15 PM

Re: How to prevent multiple child forms opening

What can I change in this code that opens my child forms to prevent it

from opening new instances?
>
Dim frmCustomers As New Customers()
frmCustomers.Md iParent = Me
frmCustomers.Wi ndowState = FormWindowState .Maximized
frmCustomers.Sh ow()

You could, for example, use a variable to hold the form instance. For
example,

Private frmCustomers As Customers

Private Sub mnuShowCustomer s_Click()
If frmCustomers Is Nothing OrElse frmCustomers.Is Disposed Then
frmCustomers = New Customers()
frmCustomers.Md iParent = Me
End If
frmCustomers.Wi ndowState = FormWindowState .Maximized
frmCustomers.Sh ow()
End Sub

**Tony K** · Mar 11 '07, 05:25 PM

Re: How to prevent multiple child forms opening

Thank you Cor. You've helped me out several times and I really appreciate
it. Thanks for the useful links.

Tony

"Cor Ligthert [MVP]" <notmyfirstname @planet.nlwrote in message
news:%23IvNZh6Y HHA.4560@TK2MSF TNGP03.phx.gbl. ..

Tony,
>
I think that you are searching for the Isdisposed method from a control
(and therefore a form).
http://msdn.microsoft.com/library/de...posedtopic.asp
>
Cor
>
>
"Tony K" <king-tony2@NOSPAMcom cast.netschreef in bericht
news:4D5FB25A-BB34-49F8-B13F-6F6816B1338F@mi crosoft.com...

>>I have a MDI application. On the menu toolstrip child forms are selected
>>from one of the menus. I don't want to play the disable/enable menu item
>>game. I have selected that open forms are added to the "Window" menu
>>item. What I'm looking for is when the user clicks on the menu item to
>>open the form, how can I check to see if it's open already and if so then
>>set the focus (if possible).
>>
>What happens now is if the menu item is clicked on 2, 3 or even 4 times,
>it opens new instances of the form each time.
>>
>What can I change in this code that opens my child forms to prevent it
>from opening new instances?
>>
> Dim frmCustomers As New Customers()
> frmCustomers.Md iParent = Me
> frmCustomers.Wi ndowState = FormWindowState .Maximized
> frmCustomers.Sh ow()
>>
>>
>Thanks,
>Tony

>
>

**Tony K** · Mar 11 '07, 05:25 PM

Re: How to prevent multiple child forms opening

Thank you, I will try it today.

Tony

"Heikki Leivo" <heikkidotleivo @cadworksdotfi. removethiswrote in message
news:pTUIh.1432 9$w55.8805@read er1.news.saunal ahti.fi...

>What can I change in this code that opens my child forms to prevent it
>from opening new instances?
>>
> Dim frmCustomers As New Customers()
> frmCustomers.Md iParent = Me
> frmCustomers.Wi ndowState = FormWindowState .Maximized
> frmCustomers.Sh ow()

>
You could, for example, use a variable to hold the form instance. For
example,
>
Private frmCustomers As Customers
>
Private Sub mnuShowCustomer s_Click()
If frmCustomers Is Nothing OrElse frmCustomers.Is Disposed Then
frmCustomers = New Customers()
frmCustomers.Md iParent = Me
End If
frmCustomers.Wi ndowState = FormWindowState .Maximized
frmCustomers.Sh ow()
End Sub
>
>
>
>

**Stephen Flynn** · Mar 12 '07, 01:25 PM

Re: How to prevent multiple child forms opening

I use the following code. It will check each open forms type, if it finds
an open form of that type, then it will bring it to the front. If not
found, then it will open it.

For Each OpenForm As Form In Me.MdiChildren
If TypeOf OpenForm Is [FormName] Then
OpenForm.Activa te()
Exit Sub
End If
Next
Dim NewForm As New [FormName]
NewForm.Visible = True

"Tony K" <king-tony2@NOSPAMcom cast.netwrote in message
news:4D5FB25A-BB34-49F8-B13F-6F6816B1338F@mi crosoft.com...

>I have a MDI application. On the menu toolstrip child forms are selected
>from one of the menus. I don't want to play the disable/enable menu item
>game. I have selected that open forms are added to the "Window" menu item.
>What I'm looking for is when the user clicks on the menu item to open the
>form, how can I check to see if it's open already and if so then set the
>focus (if possible).
>
What happens now is if the menu item is clicked on 2, 3 or even 4 times,
it opens new instances of the form each time.
>
What can I change in this code that opens my child forms to prevent it
from opening new instances?
>
Dim frmCustomers As New Customers()
frmCustomers.Md iParent = Me
frmCustomers.Wi ndowState = FormWindowState .Maximized
frmCustomers.Sh ow()
>
>
Thanks,
Tony

**Branco Medeiros** · Mar 12 '07, 01:45 PM

Re: How to prevent multiple child forms opening

Tony K wrote:

I have a MDI application. On the menu toolstrip child forms are selected
from one of the menus. I don't want to play the disable/enable menu item
game. I have selected that open forms are added to the "Window" menu item.
What I'm looking for is when the user clicks on the menu item to open the
form, how can I check to see if it's open already and if so then set the
focus (if possible).

<snip>

What can I change in this code that opens my child forms to prevent it from
opening new instances?
>
Dim frmCustomers As New Customers()
frmCustomers.Md iParent = Me
frmCustomers.Wi ndowState = FormWindowState .Maximized
frmCustomers.Sh ow()

If you're using VB 2005 you can use the My.Forms collection:

<aircode>
Dim frmCustomers As Customers = My.Forms.Custom ers

frmCustomers.Md iParent = Me
frmCustomers.Wi ndowState = FormWindowState .Maximized
frmCustomers.Sh ow()

frmCustomers.Ac tivate
</aircode>

This will show the Customers form if it's not shown already (or was
closed) and give it focus if it's already shown.

HTH.

Regards,

Branco.

**lord.zoltar@gmail.com** · Mar 12 '07, 02:25 PM

Re: How to prevent multiple child forms opening

Y'know what else works? Open the form by the name of it's CLASS.

Example: If the form's class's name is "MyForm1" and you do
"MyForm1.Sh ow", no matter how many times you click the button that
executes "MyForm1.Sh ow", the form will only open once. I don't like
this one too much myself, but it works in a pinch, and is pretty easy
to implement.

**Tony K** · Mar 15 '07, 02:45 AM

Re: How to prevent multiple child forms opening

Wow! This worked perfectly. Thanks Branco.

Tony

"Branco Medeiros" <branco.medeiro s@gmail.comwrot e in message
news:1173706663 .870367.224360@ h3g2000cwc.goog legroups.com...

Tony K wrote:

>I have a MDI application. On the menu toolstrip child forms are selected
>from one of the menus. I don't want to play the disable/enable menu item
>game. I have selected that open forms are added to the "Window" menu
>item.
>What I'm looking for is when the user clicks on the menu item to open the
>form, how can I check to see if it's open already and if so then set the
>focus (if possible).

<snip>

>What can I change in this code that opens my child forms to prevent it
>from
>opening new instances?
>>
> Dim frmCustomers As New Customers()
> frmCustomers.Md iParent = Me
> frmCustomers.Wi ndowState = FormWindowState .Maximized
> frmCustomers.Sh ow()

>
If you're using VB 2005 you can use the My.Forms collection:
>
<aircode>
Dim frmCustomers As Customers = My.Forms.Custom ers

> frmCustomers.Md iParent = Me
> frmCustomers.Wi ndowState = FormWindowState .Maximized
> frmCustomers.Sh ow()

frmCustomers.Ac tivate
</aircode>
>
This will show the Customers form if it's not shown already (or was
closed) and give it focus if it's already shown.
>
HTH.
>
Regards,
>
Branco.
>

**Cyril Gupta** · Mar 15 '07, 06:15 AM

Re: How to prevent multiple child forms opening

Hello Tony,

Here's an alternative method

If frmCustomers Is Nothing OrElse frmCustomers.Is Disposed Then
frmCustomers = New Customers()
End If
frmCustomers.Md iParent = Me
frmCustomers.Wi ndowState = FormWindowState .Maximized
frmCustomers.Sh ow()

-- You can do anything with a little bit of 'magination.

-- I've been programming so long, my brain is now software.

Wow! This worked perfectly. Thanks Branco.
>
Tony
>
"Branco Medeiros" <branco.medeiro s@gmail.comwrot e in message
news:1173706663 .870367.224360@ h3g2000cwc.goog legroups.com...
>

>Tony K wrote:
>>

>>I have a MDI application. On the menu toolstrip child forms are
>>selected
>>from one of the menus. I don't want to play the disable/enable menu
>>item
>>game. I have selected that open forms are added to the "Window"
>>menu
>>item.
>>What I'm looking for is when the user clicks on the menu item to
>>open the
>>form, how can I check to see if it's open already and if so then set
>>the
>>focus (if possible).

><snip>
>>

>>What can I change in this code that opens my child forms to prevent
>>it
>>from
>>opening new instances?
>>Dim frmCustomers As New Customers()
>>frmCustomers. MdiParent = Me
>>frmCustomers. WindowState = FormWindowState .Maximized
>>frmCustomers. Show()

>If you're using VB 2005 you can use the My.Forms collection:
>>
><aircode>
>Dim frmCustomers As Customers = My.Forms.Custom ers

>>frmCustomers. MdiParent = Me
>>frmCustomers. WindowState = FormWindowState .Maximized
>>frmCustomers. Show()

>frmCustomers.A ctivate
></aircode>
>This will show the Customers form if it's not shown already (or was
>closed) and give it focus if it's already shown.
>>
>HTH.
>>
>Regards,
>>
>Branco.
>>

**Cor Ligthert [MVP]** · Mar 15 '07, 06:35 AM

Re: How to prevent multiple child forms opening

Branco,

In all versions is the MDIChildren collection

http://msdn2.microsoft.com/en-us/lib...ichildren.aspx

Because of your message I got the impression that you did not know that.

Cor

"Branco Medeiros" <branco.medeiro s@gmail.comschr eef in bericht
news:1173706663 .870367.224360@ h3g2000cwc.goog legroups.com...

Tony K wrote:

>I have a MDI application. On the menu toolstrip child forms are selected
>from one of the menus. I don't want to play the disable/enable menu item
>game. I have selected that open forms are added to the "Window" menu
>item.
>What I'm looking for is when the user clicks on the menu item to open the
>form, how can I check to see if it's open already and if so then set the
>focus (if possible).

<snip>

>What can I change in this code that opens my child forms to prevent it
>from
>opening new instances?
>>
> Dim frmCustomers As New Customers()
> frmCustomers.Md iParent = Me
> frmCustomers.Wi ndowState = FormWindowState .Maximized
> frmCustomers.Sh ow()

>
If you're using VB 2005 you can use the My.Forms collection:
>
<aircode>
Dim frmCustomers As Customers = My.Forms.Custom ers

> frmCustomers.Md iParent = Me
> frmCustomers.Wi ndowState = FormWindowState .Maximized
> frmCustomers.Sh ow()

frmCustomers.Ac tivate
</aircode>
>
This will show the Customers form if it's not shown already (or was
closed) and give it focus if it's already shown.
>
HTH.
>
Regards,
>
Branco.
>

**Branco Medeiros** · Mar 15 '07, 05:15 PM

Re: How to prevent multiple child forms opening

Cor Ligthert [MVP] wrote:

In all versions is the MDIChildren collection
>
http://msdn2.microsoft.com/en-us/lib....forms.form.md...
>
Because of your message I got the impression that you did not know that.

<snip>

Yes, but the MDIChildren collection lists all *open* child forms. That
would mean look up the child in the MDIChildren, and create a new
instance if it wasn't there... more trouble for what the OP was
asking, I guess.

Regards,

Branco.

How to prevent multiple child forms opening

How to prevent multiple child forms opening

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