Modeless dialog created by modal dialog in Compact Framework - compact-framework

Question

I am working on a Compact Framework application. This particular hardware implementation has a touchscreen, but its Soft Input Panel has buttons that are simply too small to be useful. There are more than one form where typed input is required, so I created a form with buttons laid out like a keypad. The forms that use this "keypad" form are modal dialogs. When a dialog requiring this "keypad" loads, I load the "keypad" form as modeless:
private void CardInputForm_Load(object sender, EventArgs e)
{
...
keypadForm = new KeypadForm();
keypadForm.Owner = this;
keypadForm.SetCallback(keyHandler);
keypadForm.Show();
}
The SetCallback method tells the "keypad" form where to send the keystrokes (as a Delegate).
The problem I'm having is that the modeless "keypad" form does not take input. It is displayed as I expect, but I get a beep when I press any of its buttons, and its caption is grayed-out. It seems like the modal dialog is blocking it.
I've read other posts on this forum that says modal dialogs can create & use modeless dialogs. Can anyone shed light on this situation? Is there a problem with my implementation?

Answer 1

I found the answer: Set the keypad form's Parent property, not its Owner property, to the form instance wanting the keystrokes. The keypad dialog's title bar stays grayed out, but the form is active.
private void CardInputForm_Load(object sender, EventArgs e)
{
// (do other work)
keypadForm = new KeypadForm();
keypadForm.Parent = this;
keypadForm.Top = 190; // set as appropriate
keypadForm.Show();
}
Be sure to clean up when done with the parent form. This can be in the parent's Closing or Closed events.
private void CardInputForm_Closing(object sender, CancelEventArgs e)
{
// (do other work)
keypadForm.Close();
keypadForm.Dispose();
}
There are two panels on the keypad form, one with numerals and one with letters and punctuation that I want. There is also an area not on a panel that is common to both, containing buttons for clear, backspace, enter/OK, and cancel. Each panel has a button to hide itself and unhide its counterpart ('ABC', '123', for example). I have all the buttons for input on the keypadForm fire a common event. All it does is send the button instance to the parent. The parent is responsible for determining what action or keystroke is desired. In my case I named the buttons "btnA", "btnB", "btn0", "btn1", "btnCancel", etc. For keystrokes, the parent form takes the last character of the name to determine what key is desired. This is a bit messy but it works. Any form wishing to use the keypad form inherits from a base class, defining a method for callback.
public partial class TimeClockBase : Form
{
public TimeClockBase()
{
InitializeComponent();
}
// (other implementation-specific base class functionality)
public virtual void KeyCallback(Button button)
{
}
}
The click event on the keypad form looks like this.
private void btnKey_Click(object sender, EventArgs e)
{
// play click sound if supported
(Parent as TimeClockBase).KeyCallback(sender as Button);
}
The method in the parent form looks like this.
public override void KeyCallback(Button button)
{
switch (button.Name)
{
case "btnCancel":
// setting result will cause form to close
DialogResult = DialogResult.Cancel;
break;
case "btnClear":
txtCardID.Text = string.Empty;
break;
// (handle other cases)
}
}