Hiding and Showing Forms in Visual Basic

When developing a Windows application using Visual Basic it is highly likely that the application will consist of multiple forms (otherwise known as windows). It is unlikely, however, that all of those forms will need to be displayed as soon as the application starts up. In fact, it is likely that most of the forms will remain hidden until the user performs some action that requires a form to be displayed.

In this chapter we will cover the topic of hiding and showing forms when developing applications in Visual Basic.

Creating a Visual Basic Application Containing Multiple Forms

Before we can look at hiding and showing Forms we first need to create an application in Visual Studio which contains more than one form. Begin by starting Visual Studio and creating a new Windows Application project called vbShowForm (see Creating a New Visual Basic Project for details).

Visual Studio will prime the new project with a single form. Click on the Form to select it and, using the Properties panel change the Name of the form to mainForm. Next we need to add a second form. To do this, click on the Add New Item in the Visual Studio toolbar to invoke the Add New Item window:

The Add New Item window allows new items of various types to be added to the project. For this example we jusy need to add a new Windows Form to the our application. With Windows Form selected in the window click on Add. Visual Studio will now display an additional tab containing the second form:

Switch between the two forms by clicking on the respective tabs. With Form2 visible click on the form and change the name of the form in the Properties panel to subForm.

Now that you have created two forms, add a Button to each form by displaying the Toolbox and dragging a Button onto each form.

Now that we have created an application with two forms the next step is provide a mechanism for hiding and showing subForm. Before doing that, however, we first need to understand the difference between modal and non-modal windows.

Understanding Modal and Non-modal Forms

A Windows form can be displayed in one of two modes, modal and non-modal. When a form is non-modal it means that other forms in the other forms in the application remain accessible to the user (in that they can still click on controls or use the keyboard in other forms).

When a form is modal, as soon as it is displayed all other forms in the application are disabled until the modal dialog is dismissed by the user. Modal forms are typically used when the user is required to complete a task before proceeding to another part of the application. In the following sections we will cover the creation of of both modal and non-modal forms in Visual Basic.

Writing Visual Basic Code to Display a Non-Modal Form

We are going to use the button control on mainForm to display subForm when it is clicked by the user. To do this double click on the button control to display the Click event procedure. In this event procedure we want to call the Show() method of the subForm to make it display. To achieve this, modify the Click event handler as follows: