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c# windows forms create generic form [duplicate]

I'm using vb.net (vs2010). I'm moving some winforms to a dll. I have a form that inherits from the one which has some subs and functions (like a test app).
My original form is: (.designer)
Partial Class Form1(Of T)
Inherits System.Windows.Forms.Form
....
End Class
Form itself contains code and a toolbar.
My test form is: (.designer)
Partial Class TestForm
Inherits Form1(Of Class1)
I get "Cannot create an instance of Form1`1[T] because Type.ContainsGenericParameters is true" when VS try to load the designer. App is usable. I can build and run the project without errors, but I need to add controls and some code to each new form.
I tried many ways:
Visual Studio 2008 Winform designer fails to load Form which inherits from generic class
How can I get Visual Studio 2008 Windows Forms designer to render a Form that implements an abstract base class?
http://www.codeproject.com/Questions/419770/Csharp-reflection-GetValue-from-a-field-in-generic
http://madprops.org/blog/Designing-Generic-Forms/
All examples are for C#, and I don't know if I'm missing something...
Is this a bad design ? I know this is a VS bug but still it seems everyone fixed it by these links.
EDIT:
I'm building a DLL. Form1 is on this DLL and TestForm is in a new project. Those links works if I'm in the same project (a.k.a. the dll).
Thanks!

Is this a bad design ? I know this is a VS bug
Bad design, not a VS bug. What you are trying to do is fundamentally incompatible with the way the Winforms designer works. It has strong WYSIWYG support, the designer creates an instance of the form's base class and allows code in that base class to run at design time. Which is why, for example, you can set the BackgroundImage property and it is immediately visible in the designer. The Form.OnPaintBackground() method paints it. The designer is not involved at all, it just sets the property.
To make that work, it must be able to create the base class object. It can't in your code, it doesn't know what kind of T to use. Not an issue when you design Form1, the T isn't needed yet since it derives from Form and creating an instance of Form is not a problem. Big issue when you design TestForm.
You'd probably argue that it should use Class1 as the T. It doesn't, the odds that it can use Reflection to discover the generic type argument from TestForm are exceedingly low. That requires the type to be compiled first. That's a chicken-and-egg problem at design time, the TestForm class gets compiled after you design it, not before or while you design.
It's not like you completely cannot use your approach. It builds and runs just fine. You just have to live without design time support for TestForm. That's usually a deal breaker, you have to re-consider your design.

VS.Net2013 Designer removes custom controls instantiation

I have one project with my forms, etc. and one DLL-Project with UserControls and extended Controls, all with .Net4.5.1 and WinForms. A few weeks ago I did a migration from VS-Net2013 but the custom controls I'm talking about did not exist at that time. With every edit in my form inside Designer the new Form.Designer.cs is missing the instantiation of my custom gridview. All other parts regarding this control are still in the designer-code.
public class RichGridView : DataGridView { ... }
The missing part in Form.Designer.cs is:
this.dataDGV = new RichGridView(Definitions.DataType);
I can put this line back for myself into the designer-code but that's not how it should be. I was checking whether there are other files where VS might store information about the controls handled in its designer file but didn't found something. A while ago the designer has thrown away that line only a couple of times, so I could edit my form in the designer-window without problems and very seldom the instantiation was thrown away, now with every edit.
The other Project containing the DLL with my custom controls was compiled successfully and available for my Forms-Project, furthermore there was no change at all in the other project. If the point is that the custom control is outside the Forms-Project: I had to do this due to constraints in VS when dealing with UserControls regarding 32 vs 64 bit and debugging possibilities.
Not sure if there is some part of my code necessary for this question.

A partial class has multiple form

When I write a winforms application, I tend to create an Implementation.cs file for each form.
Say I have Form1.cs, I'd create a new file called Form1.Implementation.cs starting with partial class Form1.
Form1.cs just contains all the event callback methods (what the designer has done), everything else goes to Form1.Implementation.cs. It helps me write more readable code.
I wanted Form1.Implementation.cs to be a "subfile" just like Form1.Designer.cs is, so I edited .csproj file.
<Compile Include="Form1.Implementation.cs">
<DependentUpon>Form1.cs</DependentUpon>
</Compile>
After reload, however, Visual Studio automatically adds <SubType>Form</SubType> right after DependentUpon element. Doubleclicking Form1.Implementation.cs doesn't show code but a designer with another initial empty form.
It's like
"class Form1, which ISA Form, is(?) multiple forms."
I tried adding DesignerCategory attribute to class Form1, but it affects Form1.cs, as well.
Well, hitting 'Shift-F7' or 'Ctrl-Shift-0' is not a big deal.
I wonder if...
it's a glitch of Visual Studio,
the secondary(?) form really exists somehow,
it's going to blow up my winforms project someday

The only way of achieving what you tried is by adding <DependentUpon>, which you already know. Now Visual Studio automatically adds the <SubType>Form</SubType> for any class derived from Form. Since your Form1.cs probably contains the line public partial class Form1 : Form, this is where the SubType is coming from.
The other files - Form1.Designer.cs and Form1.Implementation.cs may contain only partial class Form1, but since partial class definitions across multiple files are still effectively one class definition, Visual Studio detects that it still inherits Form. I believe you may already know that, but just in case here's the MSDN article about the partial keyword. Don't worry about there being multiple instances of Form in this scenario. Remember this still is just one class - Form1, no mater over how many files you spread it.
In the end, all code files containing classes (even partial!) inheriting Form (or UserControl) are automatically opened in the Designer. This behaviour is by design.
The solution here is simple - either make a code file defining a separate class not based on Form, or just use F7 to view the code of that file in Solution Explorer, however annoying that may seem. It doesn't matter if that code file is <DependentUpon> anything or not. Only the inheritance of Form or UserControl matters.
The best solution though, in my opinion, would be to stick to what Visual Studio is giving you:
Designer-generated code stays in Form1.Designer.cs
Your code (what you put in Implementation), goes in Form1.cs (hit F7 to view that code instead of going to the designer)
This is an approach my team has been sticking to for a few years now. It provides a basic means of separation of Designer code and hand-coded actions. To better separate your code, use a design pattern such as MVP, as suggested by Simon Whitehead in the comments.

Designer.cs file not generated on sub-classing a subclass of System.Windows.Form

I had a Form "ParentForm" Designed in C# VS2010 with two buttons.
I wanted five forms to have the same two buttons, so i decided to write five *.cs files(subForm1.cs,subForm2.cs...subForm5.cs) derived from the "ParentForm" as base class.
Now VS2010 shows these derived classes with a form icon(ie recognizes as Forms), but does not generate a .designer.cs file for it. So the problem I am facing is that, whenever I drag a
Control into derived class form say subForm1.cs , VS2010 puts the auto-generated code into my subForm1.cs instead of subForm1.Designer.cs. Although I tried manually creating a file named subForm1.Designer.cs (which also gets detected and is put under the hierarchy of the Form icon in solution explorer) but, still the auto-generated code goes to the subForm1.cs file. How do
I tell VS2010 to patch subForm1.cs+subForm1.Designer.cs+subForm1.resx as one form subForm1.

If you want to have the designer file, Add new Windows Forms.
Then replace the inheritance from Form class to your ParentForm class.
This way any new controls you add to your child form should get added in the designer file.
Also please go through this link on Visual Inheritance

Visual studio shows endless messages "Code generation for property 'valueMember' failed."

After several days of happily hacking away on this C# app using Visual Studio 2008, I get struck by a barrage of error dialogs showing:
Code generation for property 'valueMember' failed.
Error was: 'Object reference not set to an instance of an object.'
This happens now often when I make a tiny change in the designer, e.g. shift a control a few pixels, and then try to save. Several such error dialogs appear each second, keeping me busy cancelling all those by hammering the Enter key while trying to get alt-F4 to get VS to close.
Eventually I do get VS to close and to save the changes I made. After restarting VS, I do "clean" on the entire project, then "build" and everything works fine, the app runs fine, no problems.
Until I make another slight change in the form designer.
I don't know about any property valueMember in my app.
This makes me crazy, it is a real showstopper for my project. Any help is appreciated.

Try to Close and reopen the Visual Studio. maybe it seem silly, but it works!!

You can debug the designer using another visual studio and attach to process. If you got exception it should be easy to find it that way.
In general when openning the designer the constructor and of course initializeComponent is running.

As this is happening at design time, it is likely that you have a custom control which requires a parameter or other value which does not have a default.
When in design view in Visual Studio; a control instance is created to render it on the visual editor, but if the control requires a property to be set before it can be rendered, it will result in an error.
Can you check that all custom controls have default values, and anything referenced in the constructor that cannot have a default is wrapped by DesignMode property - see http://msdn.microsoft.com/en-us/library/system.componentmodel.component.designmode.aspx.

Similiar to #Chanipoz's answer (close/re-open) my component-rich/user-controls-everywhere forms app started to compile happily after I closed down the main form designer window.
I've had this code stack for years and have never seen the error until today. Not sure where it's coming from. But, something today about having the form open in the designer made everything unhappy. Simply closing it off of the screen made it all go smooth.

Use another instance of Visual Studio to attach to the first instance of visual studio.
Go to Debug-> Attach To Process and look for the devenv.exe process. Since you'll have two devenv.exe processes running you'll probably want to pick the one with the lower ID, that's usually the first instance of visual studio that was run.

I had to face this problem. As I have found the solution below
I am facing this issue in my customized control.
we need to implement like this
[Browsable(false)]
[DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)]
public MyCustomclass _Prperty { get; set; }

I had to face this problem. As I have not found the solution (much inheritance), I can tell:
.SuspendLayout() and .ResumeLayout() may be missing in code or one of them. The same is with .BeginInit() and .EndInit(). It is expected between them, that there will be = new ... and some settings for properties. Maybe someone facing this problem would find the solution with this information.

The problem is missing initialization code for a public property on the control. This will be added for you when you add the control to the designer, but if you replace a control with a derived control, or update the component, then the designer does not know how to deal with this.
If you have a control (wincontrol) with a public property PropertyA, and you add it to a form (myForm), then the designer will add all the necessary initialization for properties into myForm.Designer.cs. Something like;
Wincontrol1.PropertyA = new List<widget>();
It is not uncommon to need to modify a control slightly, lets say we have a new control MyWinControl
public partial class MyWinControl : WinControl
{
public List<wodget> PropertyDer1;
protected List<wodget> PropertyDer2;
}
If you sub this new control for the old control in myForm.Designer.cs, then you may well encounter this issue. The reason is that PropertyDer1 has no initialization in the winforms designer. PropertyDer2 won't cause any issues because it is protected. Similarly if you had a custom component and you add a new public property after the component has been added to a form.
If however, you deleted the instance of WinControl on the form, and dragged an instance of the MyWinControl onto the form instead, the proper initialization would occur and you would not see the error. The designer will have created the new control like this
Wincontrol1.PropertyA = new List<widget>();
Wincontrol1.PropertyDer1= new List<wodget>();
There are two easy solutions that do not require hiding the property from the designer.
1. If the property doesn't need to be public, give it the right modifier
2. If the property does need to be public, then just edit the code in the myForm.Designer.cs as in the code above to add the missing initializer

If could be of help I just detected a case that brings that same error message, impossible to take away :
I am developing an application in French, and I had to create a ToolStripMenuItem with an accented word in it like "annulées".
The system generated a menu item like "annuléesToolStripMenuItem" and the accent is the culprit.
Enough to delete the item, create it again in English and the just change the Text property of the menu item.
Hope it will be of some help.