I had a requirement to set the initial focus on a
TextBox but there was a catch. When the
UserControl that contained the
TextBox appeared, there was always a
UserControl in the foreground that was providing busy information, or an error condition. Therefore the normal setting of focus on initialization or loading did not work. To make things even worse, I designed the main Window to use
Content was used to determine the
DataTemplate to use for the
ViewModel associated with the
The code used to catch the change in the
Content of a
ContentPresenter is done by creating a new
Control derived from the
public class ActionableContentPresenter : ContentPresenter
new FrameworkPropertyMetadata(new PropertyChangedCallback(OnContentChanged)));
private static void OnContentChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
var mcc = d as ActionableContentPresenter;
new DependencyPropertyChangedEventArgs(ContentProperty, e.OldValue, e.NewValue));
public event DependencyPropertyChangedEventHandler ContentChanged;
Then all that is needed in the main Window (or
UserControl) is to associate an
event handler to the
event of this
ActionableContentPresenter.ContentChanged += ActionableContentPresenter_ContentChanged;
In the case of the sample with this article, I simply check if the
Content for the
null, and if it is, the focus can be set:
private void ActionableContentPresenter_ContentChanged(object sender,
var mcc = sender as ActionableContentPresenter;
if (mcc.Content == null )
if (DisableSetFocus.IsChecked == false)
if (SetFocusTextBox2.IsChecked == false) TextBox1.Focus();
The sample has a the main content which contains a number of controls, including two
CheckBox controls. One of the
CheckBox controls will enable the set focus and the other will changes the focus from the first
TextBox to the second
TextBox. When the "Show Overlay"
Button is clicked, and control with a
Panel with a single "Close"
Button will appear. This
Panel will completely overlay the other controls in the
Window so only the "Close"
Button can be clicked. When this
Button is clicked, the overlay
Control will disappear. If the "
CheckBox is selected, there will be no focus set to any
Control on the form. However, if it is not
IsChecked, then the focus will appear in either the first or the second
TextBox, depending on if the "Focus on TextBox 2 (otherwise TextBox 1)"
Screen after "Show Overlay" button clicked
If the "Show Alternate Content"
Button is Clicked, then a
Panel with a
Button will overlay all the Controls except the
Button controls. If the "Show Overlay"
Button is clicked, the same overlay
Panel with a single
Button will appear, and, if the "Disable Focus"
CheckBox is not selected, the focus will be on the
TextBox. Otherwise there will be no focus.
Screen after "Show Alternate Content" button is clicked
Screen after "Show Alternate Content" and then "Show Overlay" buttons are clicked
Points of Interest
This ability to connect to handlers to existing
DependencyProperties should be remembered because it opens up a lot of options on doing unconventional tasks.
I have also thought about how to make this a behavior, and plan to investigate the option.
- 05/05/2016: Initial version
- 05/16/2016: Added
PriorityBinding to article and code for comparison
- 05/21/2016: Updated code to include a
ContentPresentor set focus example