Centering MessageBox, Common DialogBox or Form on applications

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• Download source - 24.7 Kb

Introduction

The .NET standard MessageBox is centered on the screen area, not on the application. This code contains a simple component which uses a hook to center the MessageBox and also other CommonDialog or Forms on the application area.

Background

This article will not explain in detail how to use a hook in a window. The component will add a WH_CALLWNDPROC hook looking for a WM_INITDIALOG message before opening the dialog. When this message occurs, the window is centered on the owner window, or the active window if the owner window is null.

Using the code

Using the code is very easy. It is the same as using the standard MessageBox.

The following static methods are available:

• DlgBox.ShowDialog(...)

  For CommonDialog and Forms.

• MsgBox.Show(...)

  For standard MessageBox, you can define the caption.

• AppBox.Show(...)

  For standard MessageBox with Application.ProductName as caption.

• ErrBox.Show(...)

  For standard error MessageBox with message or exception.

Example: the following code displays a centered OpenFileDialog:

DlgBox.ShowDialog(new OpenFileDialog());

Example: the following code display a centered exception error message:

try
{
    ...
}
catch (Exception ex)
{
    ErrBox.Show(ex);
}

It is possible to add standard buttons or icons. All the MessageBox methods are wrapped.

Example: the following example displays a centered rich message box:

AppBox.Show("Rich Application Box",
    MessageBoxButtons.YesNoCancel,
    MessageBoxIcon.Question,
    MessageBoxDefaultButton.Button2);

Points of Interest

There is a base class WindowsHook to create other hooks. The WndProcRetHook is based on this class. You can use this base class to create your own hook.

There is also a TrueScreenRect property to retrieve the true screen size on multiscreen display.

History

This version is working well since 1.1.2003.