Question

I’ve been working for a while on my Windows Forms project, and I decided to experiment with keyboard shortcuts. After a bit of reading, I figured I had to just write an event handler and bind it to the form’s KeyDown event:

private void Form1_KeyDown(object sender, KeyEventArgs e)
{
    if (e.Control && e.Alt && e.KeyCode == Keys.O)
    {
        MessageBox.Show("Ctrl+Alt+O: magic!");
    }
}

I did that the good ol’ way of opening the Properties panel of the Visual Studio designer, then double-clicking on the KeyDown event of my form to generate the Form1_KeyDown event handler. But on testing my application, the form doesn’t respond at all to the Ctrl+Alt+O keyboard shortcut. The Visual Studio designer did generate the code to bind the event handler to the form though:

private void InitializeComponent()
{
    // ...

    this.KeyDown += new System.Windows.Forms.KeyEventHandler(this.Form1_KeyDown);

    // ...
}

So I tried adding a Console.WriteLine() call to the handler to check that it was being called at all, but no luck on that either.

Also, I tried to set a breakpoint on the event binding call (shown just above) and found that the program reaches that breakpoint just fine. But any breakpoints I set within the method definition itself are never reached.

To make sure I was doing the first few steps correctly, I tried repeating them with:

• A new form in the same solution.
  Same issue: the form doesn’t respond when I press my Ctrl+Alt+O keyboard shortcut and the debugger isn’t even stepping into the event handler. Tried this again and it works.

• A brand new WinForms solution.
  It works perfectly: the message dialog appears (the Console.WriteLine() call also works).

So I’m quite lost here. What’s preventing all the forms in this one project from receiving KeyDown events?

Answer 1

Does your form have KeyPreview property set to true?

Form.KeyPreview Property

Gets or sets a value indicating whether the form will receive key
events before the event is passed to the control that has focus.

http://msdn.microsoft.com/en-us/library/system.windows.forms.form.keypreview.aspx