Provides properties for accessing an instance of each Windows form declared in the current project.
The My.Forms object provides an instance of each form in the current project. The name of the property is the same as the name of the form that the property accesses. For information about adding forms to a project, see How to: Add Windows Forms to a Project.
You can access the forms provided by the My.Forms object by using the name of the form, without qualification. Because the property name is the same as the form's type name, this allows you to access a form as if it had a default instance. For example, My.Forms.Form1.Show is equivalent to Form1.Show.
The My.Forms object exposes only the forms associated with the current project. It does not provide access to forms declared in referenced DLLs. To access a form that a DLL provides, you must use the qualified name of the form, written as DllName.FormName.
You can use the OpenForms property to get a collection of all the application's open forms.
The object and its properties are available only for Windows applications.
Each property of the My.Forms object provides access to an instance of a form in the current project. The name of the property is the same as the name of the form that the property accesses, and the property type is the same as the form's type.
If there is a name collision, the property name to access a form is RootNamespace_Namespace_FormName. For example, consider two forms named Form1.If one of these forms is in the root namespace WindowsApplication1 and in the namespace Namespace1, you would access that form through My.Forms.WindowsApplication1_Namespace1_Form1.
The My.Forms object provides access to the instance of the application's main form that was created on startup. For all other forms, the My.Forms object creates a new instance of the form when it is accessed and stores it. Subsequent attempts to access that property return that instance of the form.
You can dispose of a form by assigning Nothing to the property for that form. The property setter calls the Close method of the form, and then assigns Nothing to the stored value. If you assign any value other than Nothing to the property, the setter throws an ArgumentException exception.
You can test whether a property of the My.Forms object stores an instance of the form by using the Is or IsNot operator. You can use those operators to check if the value of the property is Nothing.
Typically, the Is or IsNot operator has to read the value of the property to perform the comparison. However, if the property currently stores Nothing, the property creates a new instance of the form and then returns that instance. However, the Visual Basic compiler treats the properties of the My.Forms object differently and allows the Is or IsNot operator to check the status of the property without altering its value.
The following table lists examples of tasks involving the My.Forms object.
Control one form from another form.
This example changes the title of the default SidebarMenu form.
For this example to work, your project must have a form named SidebarMenu. For more information, see How to: Add Windows Forms to a Project.
This code will work only in a Windows Application project.