Behavior to force TextBox model update to prevent trouble with the ApplicationBar

source: Joost van Schaik`s blog

A small quicky this time:

Problem:

• TextBox, Text property bound to a string in my ViewModel
• I type text in the TextBox
• I click a "Save" button on my ApplicationBar
• The string in my ViewModel is not updated. It never gets updated. WTF???

It appears the TextBox only updates it's value to a bound string when it loses focus. And a TextBox does not lose focus when you click an ApplicationBar Button. Meh.

I have found a few solutions and workarounds, and in the end rolled my own:  a very small behavior that updates the binding every time you type something in your textbox. That's a bit wasteful, but it works for me. It builds on the SafeBehavior pattern I wrote about earlier, and it's so small I post it in one go:

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