Commit freehand annotations without pressing "Save" button

Im using a default annotation control toolbar that comes with one of your winRT examples.
when i select the freehand tool, and do some lines with it , i then have to press a “Save” button to commit the lines i did to the document.

I have another button on a app bar i made, that “Saves as” the file to a new location.
I would like to know how i can call the Save to commit the free hand changes in the “Save as” button

All the code related to the annotations, including the annotations tool bar, is in the Tools project. You will find the code there that you want to reference in your Save As button. Start with FreehandCreate file.