The Form's KeyPreview Property

To understand this property,lets look on the following example:

Start new project, and add 1 Command Button (named Command1) to your form, verify that the Form's KeyPreview property is set to "False".Add the following code to your program:

Private Sub Command1_KeyPress(KeyAscii As Integer)
    Print "Button Pressed"
End Sub

Private Sub Form_KeyPress(KeyAscii As Integer)
    Print "Form Pressed"
End Sub

The code above will print "Button Pressed" on the form when the Command Button's KeyPress event will be executed, and print "Form Pressed" when the Form's KeyPress event will be executed.
Run the program and press any key on the keyboard."Button Pressed" is appearing on the form, but "Form Pressed" isn't appearing.

The Form's KeyPress event hasn't been executed.When the KeyPreview property is "False", if any control is found on the form (the command button in this case),It will get all the Key events (KeyPress, KeyDown and KeyUp)instead of the form.

To allow the Form's Key events be executed, set the KeyPreview property to "True".Lets try it. Set the KeyPreview property to "True", run the program again and press any key.The Form's KeyPress event has been executed,in addition to the Button's KeyPress event that been executed too.
Notice That the form's KeyPress event executed before the Button's event.