Question

Hopefully a simple starter question from a newbie…

I have a TextBox whose Text property is bound to a ViewModel and DependencyProperty.

When I click on the TextBox I want a second TextBox (an ‘Editor’ TextBox) to be assigned the same binding as the first. The outcome being that editing the second ‘Editor’ TextBox will update the first.

Ultimately I want to be able to click any TextBox and edit it in the same ‘Editor’ TextBox.

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My Solution using Option 2… Thanks!!:

    private void m_sourceTextBox_MouseDoubleClick(object sender, MouseButtonEventArgs e)
    {
        TextBox sourceTextBox = sender as TextBox;
        if (null != sourceTextBox)
        {
            BindingExpression sourceBindExpression = sourceTextBox.GetBindingExpression(TextBox.TextProperty);

            if (sourceBindExpression != null && sourceBindExpression.ParentBinding != null && sourceBindExpression.ParentBinding.Path != null)
                m_editorTextBox.SetBinding(TextBox.TextProperty, sourceBindExpression.ParentBinding);
        }
    }

Answer 1

I can think of two ways of doing this

The first, is to have a SelectedText property in your ViewModel that your EditorTextBox is bound to, and set this value when you click on any of the other TextBoxes. For this to work, you’ll probably need something like an AttachedCommandBehavior so you can attach a Command from the ViewModel to the Click or Focus event of the TextBox.

The other way I can think of doing it is just to do it in code-behind. In the Click or Focus event of each TextBox, get the BindingExpression for the selected TextBox’s TextProperty, and copy the binding to the EditorTextBox.Text.