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Child form's controls not displaying correctly

I am using an MDI form in which I have given option tool strip menu item as a call to a new child form. On the child form I have some buttons and DataGridView. But when I click the child form option the buttons and DataGridView are not displaying correctly. Provided I have already set the isMdiContainer property to true of MDI form.
The scenario runs successfully when I simply show a form, but the problem occurs when I use the form as a child form. Here is the code which I wrote in a tool strip menu item click:
frm_bank_master myfrm = new frm_bank_master();
myfrm.MdiParent =this;
myfrm.Show();

MDIChild toolbar displays in MDIParent

I have an MDIChild that has a toolstrip. When I open the window the toolstrip is displayed alongside the toolstrip of the MDIParent. The searching I have done suggests that this is normal behaviour unless the child is opened modally. Can I not stop this from happening and fix the toolstrip to the window it is meant to be displayed on?
This is the MDI Parent
This is the MDI Child
This is what happens when I open the child and what I want to stop happening.

Set the AllowMerge Property of the MenuStrip of the Child form to false.
From MSDN
Use the AllowMerge property to enable multiple-document interface (MDI) children to combine their respective menus in the MDI parent.
When this property is set the true, the menus will combine (just like in your case). When false, they won't

Display UserControl as popup window

I have a UserControl where I have some buttons and textboxes. I was wondering how I can display that UserControl when a user clicks a button.

A user control cannot be a 'popup window', that requires a toplevel window. A form. You can put the user control in a form and use the form's Show() method to make it visible.
Fwiw, turning a user control into a toplevel window is technically possible with the SetTopLevel() method. It isn't worth the hassle, it won't behave like a proper one.

You should paste the user control on a windows form and then make it a modal window. Make a object of that form and then call object.open();

c# Add HelpButton to a MDI child form at run time

i'd like the following code to work (where this. is a MDI child form)
this.HelpButton = true;
this.HelpButtonClicked += HandleHelpButtonClicked;
this.Refresh();
this code is being called after the mdi child form is displayed.
I wonder if i need to find some way of redrawing the title bar?
David

From the MSDN docs:
The value of the HelpButton property is ignored if the Maximize or Minimize buttons are shown.

Interacting with a form without it activating

I'm trying to implement code-completion popup window in my project. The window is derived from Form. It contains two controls: custom list derived from UserControl (it shows completion possibilities with icons) and a VScrollBar.
When the popup appears, it doesn't steal focus from the editor (form's ShowWithoutActivation is overriden to return true) and the editor sends certain keystrokes to the popup so the user can interact with it using keyboard. So far it works like a charm.
The problem is, I want to allow the user to use mouse as well. But, when the user clicks into the popup window, its form activates and steals focus from the editor. I can react to this by giving the focus back to the editor, I have even set up a Timer to do this regularly, but apart from being a poor solution, the title bar of the editor always flickers when this happens (when the popup is clicked).
Is there any way to interact with the popup form (using mouse) that doesn't make the form activate?
The ShowWithoutActivation's documentation reads: "If your non-activated window needs to use UI controls, you should consider using the ToolStrip controls, such as ToolStripDropDown. These controls are windowless, and will not cause a window to activate when they are selected." This seems exactly like the thing I need, but I want to use a custom control and a scroll bar.
The same problem would be with a tooltip that shows these two arrows to switch method overloads (known from VS) - the whole form would use no controls at all (only render the text and the arrows), but when clicked, it should not activate. The problem could be summarized up to "How to create a form that would never activate, but allow the user to interact with certail controls inside?".
Thanks.

Just override the onFocus event...
public partial class myListBox:ListBox
{
protected override void OnGotFocus(EventArgs e)
{
}
}

The issue is that you're using a Form for this rather than building some custom control that doesn't run in its' own UI thread like a Form does.
The flashing and highlighting is handled by windows whenever a Form activates/focuses. The only thing I cay think of is to make your Form borderless and create/draw/handle your own title bar that doesn't flash when focused.

OK, I may have found a solution. The key seems to be WM_MOUSEACTIVATE message, which the popup form must intercept and respond with MA_NOACTIVATE. But there's a catch - the control derived from UserControl still grabs focus when clicked (the scrollbar luckily doesn't anymore). The problem seems to be in the UserControl.OnMouseDown method, which internally puts focus on the control. There are some ways to fix this:
derive the control from Control instead of UserControl
override the OnMouseDown method and not call base.OnMouseDown there
make the control's CanFocus property return false, but this seems not possible, because that means to make the control either not visible or not enabled, which is both undesirable
The last case when the popup form steals focus seems to be when its resizing (using mouse) ends. But it is safe here to call Owner.Activate() as a result to Activated event...