General Question About WPF Control Behavior and using Invoke
- by Phil Sandler
I have been putting off activity on SO because my current reputation is "1337". :)
This is a question of "why" and not "how". By default, it seems that WPF does not set focus to the first control in a window when it's opening. In addition, when a textbox gets focus, by default it does not have it's existing text selected. So basically when I open a window, I want focus on the first control of the window, and if that control is a textbox, I want it's existing text (if any) to be selected.
I found some tips online to accomplish each of these behaviors, and combined them. The code below, which I placed in the constructor of my window, is what I came up with:
Loaded += (sender, e) =>
{
MoveFocus(new TraversalRequest(FocusNavigationDirection.Next));
var textBox = FocusManager.GetFocusedElement(this) as TextBox;
if (textBox != null)
{
Action select = textBox.SelectAll;
//for some reason this doesn't work without using invoke.
Dispatcher.Invoke(DispatcherPriority.Loaded, select);
}
};
So, my question. Why does the above not work without using Dispatcher.Invoke? Is something built into the behavior of the window (or textbox) cause the selected text to be de-selected post-loading?
Maybe related, maybe not--another example of where I had to use Dispatcher.Invoke to control the behavior of a form:
http://stackoverflow.com/questions/2602979/wpf-focus-in-tab-control-content-when-new-tab-is-created
