Winforms TextBox gets focus but doesn't capture keyboard input

Question

This has me baffled.

I've written a popup box which consists of a WinForms UserControl hosted inside a WindowsFormsHost, which, in turn, is hosted in a Primitives.Popup which is displayed on the screen. The whole application is WPF, but this control was lifted from an earlier application written in WinForms.

The popup is activated by an external event (an incoming phone call from a CTI Server).

Inside the UserControl is a textbox control. When the user clicks in the text box, I call the Focus method on the Popup, then call the Focus method on the textbox. The textbox gets the focus. I can be fairly sure of that because the box shows a cursor after clicking in it, and also I have a "GotFocus" event handler that prints a debugging message.

However, if there was another program active at the time the incoming event occurs, any keys that are pressed on the keyboard continue to go to that program, not to the text box. Only if the user clicks in another part of my application (i.e., part of the screen outside the popup) to make it the active program, and then clicks in the text box is the text box able to receive keyboard input.

I hope I've given enough information without overwhelming you with the myriad of details. If there's something else anyone needs to point me in the right direction, I'll be happy to provide it.

kennyzx kennyzx · Accepted Answer · 2014-09-24T01:42:25

Because the WinForm TextBox is hosted, setting focus on it does not activate the hosting WPF Window. Add a line to activate the Window.

private void TextBox_Click(object sender, EventArgs e)
{
    this.Activate(); //activate the Window
    (sender as System.Windows.Forms.TextBox).Focus();
}

Winforms TextBox gets focus but doesn't capture keyboard input

1 Answers