If you've written Windows applications for the desktop you'd probebly used this property. On devices what you used to have to do was to write a 'hack' something similar to the following when calling sub-forms from within your application:
using (Form1 form1 = new Form1())Quite ugly huh! You had to set the Text property for the form to blank before calling a sub-form so that you wouldn't get two entries visible in the memory applet under Settings. P/Invoking SetForegroundWindow was also required to ensure your app would come back to the foreground after closing the sub-form if you had viewed other windows during the lifecycle of the sub-form.
this.Text = "";
string str = this.Text;
this.Text = str;
Now all you have to code is the following:
using (Form1 form1 = new Form1())Lovely!
form1.Owner = this;