Can we access MdiParent form controlsevent from child form ?

Question

1.I have 3 forms into my project mainform(MdiParent),child1 and child2.
2.Inside mainform contains two controls panel1,toolstrip1 and inside toolstrip1 control I added two Items toolstripbutton1,toolstripbutton2.
3.Child1 contains button1 control.
4. If mainform (MdiParent's) form's toolstripbutton1 click event I enter following code.

private void toolStripButton1_Click(object sender, EventArgs e)
       {
toolStripButton1.Enabled = false;
child2 fr2 = new child2();
if (panel1.Controls.Count > 0)
{

                         foreach (Form afrm in this.panel1.Controls)
{
         afrm.Close();
   }

}
         fr2.MdiParent = this;
this.panel1.Controls.Add(fr2);
fr2.Show();
fr2.FormClosed += (sen, eventarg) => { toolStripButton1.Enabled = true; };
}

Question : From above mentioned situation I have three questions -
If I click child1 forms button1 then I want to open child2 form inside Mdiparent form's panel1 control. How can I do this? How can I access MdiParent panel1 control from child1 form's button click event? Can I directly call above specified event from child1 button click?

Vulpes · Answer

It's not possible for a panel to be an MdiContainer. If it were then the Panel class would have an IsMdiContainer property which it does not. Also if a form is opened within a panel then it can no longer be an MDI child of the containing form which is why the MdiParent property of child2 is null even though you've tried to set it to mainform. If you want to open child3 within the panel on mainform then you'll have to forget about it being an MDI child change the Modifiers property of panel1 from private to internal and use code such as this instead: private void button1_click() { child3 cf3 = new child3(); mainform mf = (mainform)Application.OpenForms[mainform]; cf3.TopLevel = false; mf.panel1.Controls.Add(cf3); cf3.Show(); }

kishor choure · Answer

Yes sir I get it. When panel is use to open the child or any form then there is no need of mdiparent container required for the opening of child form. Thank you sir it's very useful to me.

kishor choure · Answer

but panel prevent to open child3 form inside mdiparent. Let me tail you one by one 1. I open main form mdiparent 2. On toolstripbutton1_clik I open child2 form inside panel1 of mdiparent 3. After that on button1_click event of child2 I am going to open the child3 form inside panel1 of mdiparent but its not work

Vulpes · Answer

That won't stop them from opening but the panel will 'float' on top of the child forms and so you might not be able to see them properly. If you want to open child2 in panel1 on mainform then you'll need to set the IsMdiContainer property to false and then change the code to open child2 to the following: private void toostripbutton1_click() { child2 c = new child2(); c.TopLevel = false; this.panel1.Controls.Add(c); c.Show(); }

kishor choure · Answer

I think it's not opening becoz in my mdiparent contains panel1 control . so can you tail me how to open child inside mdiparent's panel1 control. When I add panel1 inside mdiparent and open child2 inside it after button1_click of child2 form child3 form will open but not within mdiparent container. If I remove panel1 from mdiparent same code inside button1_click of child2 form will open the child3 inside mdiparent container. try this and help me to open the child3 form inside mdiparent's panel1 control after click of button1 of child2.

Vulpes · Answer

I tried the code myself and it worked fine so I don't understand why it's not working properly for you :-/ I assume you must have set mainform's IsMdiContainer property to true otherwise you'd get an exception. As this.MdiParent is evidently null the only other thing I can suggest is to try and get a reference to mainform using other means. Try this instead: private void button1_click() { child3 cf3 = new child3(); cf3.MdiParent = Application.OpenForms[mainform]; cf3.Show(); }

kishor choure · Answer

yes sir I makes child1 form as mdichild of mainform inside mainform toolstripbutton1_click event as private void toostripbutton1_click() { child2 c=new child2(); c.mdiparnet=this; c.show(); } but when I tried to open child3 form inside mdiparent from child2 form's button click event as class child2 { private void button1_click() { child3 cf3=new child3(); cf3.Mdiparent=(Mainform)this.Mdiparent; cf3.show(); } } from above code it opens my child3 form but not within the mainform (mdiparent) container. please help me.

Vulpes · Answer

Are you sure that child1 is in fact an MDI child of mainform? In other words did you set it's MdiParent property to 'this' when launching it from mainform?

kishor choure · Answer

Sir I have checked from debugger mainform object 'mf' is null. Another problem I am facing that I am unable to open my child3 form inside mdiparent form on button_click event on child2.

Vulpes · Answer

By using the debugger or MessageBox.Show are you able to tell me what's null here? On the face of it it can't possibly be 'mf' because every MdiChild must have have an MdiParent. Also I wouldn't have thought that it could be 'toolStripButton1' either if you've added this from the VS designer rather than dynamically in code.

kishor choure · Answer

Sir I have tried above mentioned code but it gives me following error Object reference not set to an instance of an object. Tail me the second method to call the events of parent form from child form.

Vulpes · Answer

If you change the Modifiers property of toolStripButton1 from private to internal in the Properties Box then you should be able to click it programatically from child1's button1_Click eventhandler using the following code: // get reference to mdiparent form mainform mf = (mainform)this.MdiParent; // click toolStripButton1 mf.toolStripButton1.PerformClick();

Can we access MdiParent form controls,event from child form ?