Develop Reference

Child form appearing underneath controls on parent form

I have a C#, .net, Windows Forms application. I have a form set as an MDI container on which I dynamically add buttons. Clicking a button opens a child form. However, the buttons I created appear on top of the child form instead of the child form appearing over (and covering) everything on the parent form. What am I doing wrong?
Here's how I add the buttons to the form:
Button btn1 = new Button();
btn1.BackColor = ColorTranslator.FromHtml("#456EA4");
btn1.Text = department.DepartmentName;
btn1.Location = new System.Drawing.Point(posX, posY);
btn1.Size = new System.Drawing.Size(sizeX, sizeY);
btn1.Font = new System.Drawing.Font("Calibri", 40F, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, ((byte)(0)));
btn1.ForeColor = Color.WhiteSmoke;
btn1.TabStop = false;
this.Controls.Add(btn1);
Here's is where I open the child form:
frmToBuildFromSchedule frmToBuild = new frmToBuildFromSchedule(department);
frmToBuild.FormClosed += new FormClosedEventHandler(frmToBuildFromSchedule_FormClosed);
frmToBuild.MdiParent = this;
frmToBuild.Show();
Here is the result:

You are putting the buttons directly on the parent MDI form, which is not typical of an MDI style application. Instead, put the code that is currently in the click event of your buttons in a menu option or a ribbon button (those can also be dynamically created).
Alternatively, create a child form, maximize it, and place your buttons on that.

I think the answer by sam on the posted duplicate link is interesting. Rather than using MDI, set form.TopLevel = false; and add the form as a child control. I'm not sure if there are any downsides to this approach.
Form fff = new Form();
fff.Controls.Add(new Button { Text = "Button1" });
fff.Load += delegate {
Form ffff = new Form { TopLevel = false };
fff.Controls.Add(ffff);
ffff.Visible = true;
ffff.BringToFront();
};
Application.Run(fff);

Set Location for new form

I use below code to make lightbox effect and it works as i expected. However if i move the parent form it still pop-ups on the center of the screen.
// Execute this code from parent form
Form f = new Form();
f.ShowInTaskbar = false;
f.BackColor = Color.Black;
f.Size = this.Size;
f.FormBorderStyle = System.Windows.Forms.FormBorderStyle.None;
f.StartPosition = this.StartPosition;
f.Opacity = 0.6;
f.Show();
So i changed the above code like below;
f.StartPosition = FormStartPosition.CenterParent;
However it still doesn't pop-up center of the parent form.
Also i tried below, It didn't work too;
f.SetBounds(this.Location.X, this.Location.Y,this.Width, this.Height);
I already tried the solutions here;
Show a child form in the centre of Parent form in C#
They also didn't work.
What i want to do is, creating a second form with the same size and same location.

Just changing this line;
f.Show();
to this line, It worked;
f.ShowDialog();

How to open an MDI parent by clicking on a button in C#?

I have two forms; form 1 which contains the button button1 and MDIParent form.
By clicking the button1 I want to be redirected to the MDIparent form.
I am using the following code in click event of the button1
MDIParent f = new MDIParent();
f.ShowDialog();
However, the code gives no response when the button is being clicked.

You Must set Parent Form Property (IsMdiContainer = True)
MDIParent f = new MDIParent();
f.MdiParent = this;
f.Show();

How can i Remove Maximize,Minimize and Close icon in MDI Menustrip

iam using C#.Net Windows Application.In my project have different module that will be used by MDI..
now what the problem is,i can open a new form mean they will display maximize,minimize and Close icon in both MDI and Menustrip.See Below Image...
How can i remove child forms icons(Maximize,Minimize and Close) from MenuStrip
Thanks in Advance...

In winforms the area where those buttons are is called ControlBox if you do not want them to be displayed you should set the ControlBox property of the form to false
childForm.ControlBox = false;
But as pointed out in the comments you could use your forms as UserControls by just setting its TopLevel property to false
Form childForm = new Form()
childForm.TopLevel = false;
childForm.Parent = MainForm;
childForm.Show()
Doing that you can acomplish the same final result as an MDI form

I am sure this is solve for what you search
in first you should set all properties
formborderstyle = None
ControlBox = false
MaximizeBox = false
MinimizeBox = false
showicon = false
and DO NOT SET Windowstate = maximized
secondly when you create object from this form
form1 form= new Student();
form.MdiParent = this;
form.Dock = DockStyle.Fill;
form.Show();

Mdiparent and SplitContainer

I am using a SplitContainter in MDI parent Form.
My problem is I loaded a form in panel1 named First Form. In this First Form with a button I load SecondForm in panel2.
I am using this code:
Form In_but = new SecondForm();
In_but.MdiParent = this.ParentForm;
In_but.TopLevel = false;
this.splitContainer1.Panel2.Controls.Add(In_but);
In_but.Show();
But it's not working. The error is: does not contain definition splitContainer1.

From looking at your code sample, I suspect your problem is when you refer to this.splitContainer, this is your 'First form' on panel 1, and your SplitContainer is on this.ParentForm.
I'd suggest changing that line to this.(ParentForm as <whatever class your parent form is>).splitContainer1.Panel2.Controls.Add(In_but);

try this
frmChild frmChild = new frmChild();
frmChild.TopLevel = false;
frmChild.Parent = this.splitContainer3.Panel2;
frmMasterlistAdministrationAdd.Show();

frmTest fs = new frmTest(); //frmTest is the form that you going to call
fs.MdiParent = this; //the main form is a mdiform and have a splitcontainer with
//two panels
this.splitContainer1.Panel2.Controls.Add(fs); //add the fs form to the panel2
fs.Show(); //show the form