Develop Reference

Unable to display Child form on top of main form's controls

Windows 7 pro 64 bit, VS2015 or VS2019
Hi,
I have a C# Win Form with many various controls.
I defined the main form as MDI parent and built an MDI child form with it's own controls, activated by a menue item in the main.
The child form builds nicely, but it is always displayed under the main form's many different controls.
I have tried many remedies, non of whch solved the problem.
I'v Set the child form as TopMost = true; TopLevel = true; each or all, for no avail.
Have moved from VS2015 to VS2019 community - Same.
I have been wasting hours to solve something that seems to be strightforward.
Can anyone help me out of this?
//In Main Form with menustrip, ComPortSetup is a standard winform class with some controls
private void portSetupToolStripMenuItem_Click(object sender, EventArgs e)
{
ComPortSetup comPortSetup = new ComPortSetup();
comPortSetup.MdiParent = this;
comPortSetup.TopMost = true;
comPortSetup.TopLevel = true; //Can not change programmatically
comPortSetup.Show();
}

That is how MDI works, there is no way around that.
All controls on the MDI Parent form will take away "client" space for the MDI child forms. And thus they will always be shown on top of any MDI Child form.
In other words, the MDI child forms can only use the space that is on the MDI Parent form that is not occupied already by other controls.
What you can do is put a panel on the MDI Parent form, and for example dock it to the left. Then put your "main" controls on that panel. The MDI Child forms will use whatever space is left on your MDI Parent form.
You could put a splitter control next to this panel so you can make it larger or smaller, or make it slidable so the panel comes forward when your mouse is near it, and hides itself again when the mouse is moving away from it.
Another approach you can try, is not making it MDI anymore and set the parent of the "child" forms yourself. But this will most likely cause other problems.
I would try the first approach, the panel on the mainform, docked to the left with a splitter control next to it.

I am not sure, but I believe that when using MDI forms, it is not expected that the parent has its own controls on the main form area, otherwise you will experience this exact problem.
So there are a couple of ways around this.
Firstly you can place a Panel on your parent form, and then your child can be added to the Panel.
This is now "proper" MDI control however, but it might allow you to achieve what you want.
ChildForm child = new ChildForm();
parentPanel.controls.add(child); //ParentPanel needs to already be on main form
Or the other method is to put your Parent Controls either on a MenuStrip (like MS Word) or you can use a Floating Dockable child form (think Visual Studio) which is then always visible.
If you want to do the latter, then I would suggest DockPanelSuite control to help you with this
https://github.com/dockpanelsuite/dockpanelsuite

How to detect that a modal form is opened from a child form? (C# & VS2017)

Maybe it's a silly question but I can't find a solution.
I have an MDI form with multiple children. There is one that I could say is the main one.
To detect that the principal is no longer used and another child form is used I use the 'Leave' event which works very well.
The problem is when from the mdi form, a modal type (.ShowDialog ()) is executed, the Leave event doesn't happen in the child form.
Any suggestion or comment on how to get it is welcome.

you can use this
to just use the current class which is in your situation the (main) .

I solved it this way:
From the MDI form, from where the modal forms are called, I search for the child forms and if it is the "main" one, I call a public function that does the same as the Leave event of the "main" form:
foreach (Form childform in this.MdiChildren)
{
if (childform.Name.Equals("MyMainForm"))
{
var formMain = (MyMainForm)childform;
formMain.stopTimer();
}
}
It may be a cumbersome solution, but it is functional.

Add a form to a MDI child

In Form1 I'm enabling IsMdiContainer and I added a MenuStrip. In Form1_Load I "new" Form2 and I'm assiging Form2.MdiParent to this which is Form1. I'm also maximizing Form2 and this operation works well.
In Form2 I have a treeView on the left side of the form and on the right side of the form I would like to display a number of different forms with various editing capabilities which will be dependent upon the node or level selected in the treeView.
I would like to create a number of different forms for editing data that would be displayed in Form2 depending on the selection from the treeView. I can't seem to add a form to the MdiChild and I've been seeing some posts where adding a form to a form may create some programming problems which I'm not sure about.
I really don't have any code to paste into this post because nothing seemed to work except for the Mdi Parent and Child relationship which was pretty simple.
Thanks in advance for any help.

There is a lot of information on this subject, but some documentation can be difficult to understand for some new developers. Follow these steps:
Open Visual Studio
Create a Windows Form Application
Click your Form
Go to Properties for that Form
Minimum Size : 1366 pixels by 768 pixels.
Launch Maximized
The important element is IsMdiContainer
Open your Toolbox.
Go to Menus
Drag FileMenu onto your Form
Build your Menu
Then go to Solution Explorer
Right-Click Add Item
Add another Form
I left mine as Form2 (In a real program, not a good name).
So within those fifteen steps, we have all that we need to accomplish our goal. So what we will do to finish our task is:
Go back to our First Form
Go to our FileMenu
Double Click on the menu button you wish to link.
It will load a code view, inside the area put this:
Form2 newFrm = new Form2();
newFrm.MdiParent = this;
newFrm.Show();
What this code is doing is three distinct things:
Line 1: It is actually calling our object, in this case a second form. It is actually building our object for us.
Line 2: Is actually linking our second form to our current form, this is physically turning our second form into a Child Form.
Line 3: This is actually physically showing our second form when the button is clicked.
That is all you need to physically show a Form.
In regards to your second question, I'm not entirely sure what your attempting to accomplish. It sounds like your trying to have a tree, then as a Node is selected the right hand side of the Form changes to specific context.
Now this isn't the nicest example, but do you mean something like this?
TreeNode node = treeView1.SelectedNode;
if (node.Text.Contains("XP"))
{
TextBox one = new TextBox();
Panel i = new Panel();
i.Dock = DockStyle.Right;
i.BackColor = Color.Black;
i.Controls.Add(one);
i.Show();
TreeFrm.ActiveForm.Controls.Add(i);
}
Not sure if that is what you are seeking. Obviously you'd want to implement a FlowLayoutPanel to make the positioning not a pain for you. Keep in mind an MDI Parent, with a Child Form acting as a MDI Parent will not work very well. As most things will default to MDI Parent Forms Docking / Positioning. This example is not pretty, but I'm not entirely sure of what your asking.
Are you trying to dock other forms or components on the same form?

parent form is accessible when child form is open

I have created a parent form and a child form in c# when i click a menu item in parent form, it opens the child form but still i access the parent form.i want that the parent form will remain inaccesible until the child form is open.please send me the code.thnks

try with this
form.ShowDialog()

Probably you should use form.ShowDialog() method instead of form.Show()
Definitely you should add a better description, at least framework you are using (WinForms?). C# is not a framework.

Use, form.Hide() process to make the Parent form to be not accessable when ever the child form opens and again give form.show() to activate the parent form.

If you want your parent form visible while showing your child form then you can do following.
form.ShowDialog(this).
Where this is the instance of your parent form.
On the other hand, if you want your parent form hide while showing child form you can do following
this.Hide();
form.ShowDialog(this)

.NET MDI child form suppress/hide caption/icon area

I have a subform (child) that I want to use in a number of parents. I'm not a professional developer (I'm an architect - I know, you can save all the jokes... :) - working solo at present). I've ended up using an MDI form with the subform as a child. I maximize the subform form and most things are fine except that although I've tried to disable all the various widgets (the subform in the designer shows NO caption/icon/button area), I get TWO icons on the left and TWO sets of buttons on the right - of which ONLY the restore button works. Either of the sets of buttons will work the one child form.
Is there any way around this? I want the subform to be "transparent" the the user - they shouldn't be aware there's a subform in use.
I've done a quick search and I'd already suppressed the actual caption as mentioned in another answer - to get the caption bar suppressed in the designer...
Is MDI the right technology, or is there a better way to have the same subform appear in multiple parent forms?
VS2008, C#, Windows 7
TIA,
Paolo

There's a WF bug that will double the glyphs if you create the MDI child form in the parent's constructor. Here's an example:
public partial class Form1 : Form {
public Form1() {
InitializeComponent();
this.IsMdiContainer = true;
var child = new Form();
child.MdiParent = this;
child.WindowState = FormWindowState.Maximized;
child.Show();
}
}
Move the child form creation code to the Load event to avoid this.