C# – WPF TextBox Not Accepting Delete Key

coutlooktextboxwpf

I have a WPF application embedded in a Microsoft Outlook 2003 window. Everything is working fine, except none of my TextBox controls accept the backspace key. I've done some research, and the problem exists only when my window is a child of the outlook window and not if it's another window (I injected it into firefox and it works fine, and if I put my wpf UserControl into a dialog window it also works). This seems to be the converse problem that people are reporting (textbox only accepting delete/arrow keys/etc), and this thread was somewhat informative (though did not fix my issue): WPF TextBox not accepting Input when in ElementHost in Window Forms

Here is my setup:
I create a WPF UserControl, which I then put in an ElementHost. I put that host into a Windows Forms UserControl, which gets put in another Forms UserControl, which gets put into a NativeWindow (I've tried removing some of the UserControl wrapping, but with no effect). This Native window then becomes a child of the Outlook window and gets placed where I need it to be in Outlook.

Does anyone have any idea? Maybe I need to handle the windows messages differently? I did some research and found out that Outlook gets a WM_COMMAND message when I hit the backspace key, but not when I don't hit anything else. Maybe it's interpreting the backspace key as a menu accelerator or something like that?

Thanks.

Best Answer

I found a way to get around this. I extended Outlook's WndProc and listened for the WM_COMMAND. Whenever it came up I tell my WPF UserControl system to send the backspace key to the currently keyboard focused control.

I can't seem to get WM_COMMAND to fire on any other keypress besides backspace so it's working pretty well right now.

Related Solutions

C# – Cross-thread operation not valid: Control accessed from a thread other than the thread it was created on

As per Prerak K's update comment (since deleted):

I guess I have not presented the question properly.

Situation is this: I want to load data into a global variable based on the value of a control. I don't want to change the value of a control from the child thread. I'm not going to do it ever from a child thread.

So only accessing the value so that corresponding data can be fetched from the database.

The solution you want then should look like:

UserContrl1_LOadDataMethod()
{
    string name = "";
    if(textbox1.InvokeRequired)
    {
        textbox1.Invoke(new MethodInvoker(delegate { name = textbox1.text; }));
    }
    if(name == "MyName")
    {
        // do whatever
    }
}

Do your serious processing in the separate thread before you attempt to switch back to the control's thread. For example:

UserContrl1_LOadDataMethod()
{
    if(textbox1.text=="MyName") //<<======Now it wont give exception**
    {
        //Load data correspondin to "MyName"
        //Populate a globale variable List<string> which will be
        //bound to grid at some later stage
        if(InvokeRequired)
        {
            // after we've done all the processing, 
            this.Invoke(new MethodInvoker(delegate {
                // load the control with the appropriate data
            }));
            return;
        }
    }
}

C# – How to make a textbox that only accepts numbers

Two options:

Use a NumericUpDown instead. NumericUpDown does the filtering for you, which is nice. Of course it also gives your users the ability to hit the up and down arrows on the keyboard to increment and decrement the current value.

Handle the appropriate keyboard events to prevent anything but numeric input. I've had success with this two event handlers on a standard TextBox:

private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
{
    if (!char.IsControl(e.KeyChar) && !char.IsDigit(e.KeyChar) &&
        (e.KeyChar != '.'))
    {
            e.Handled = true;
    }

    // only allow one decimal point
    if ((e.KeyChar == '.') && ((sender as TextBox).Text.IndexOf('.') > -1))
    {
        e.Handled = true;
    }
}

You can remove the check for '.' (and the subsequent check for more than one '.') if your TextBox shouldn't allow decimal places. You could also add a check for '-' if your TextBox should allow negative values.

If you want to limit the user for number of digit, use: textBox1.MaxLength = 2; // this will allow the user to enter only 2 digits

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