In Draftsight 2016 there used to be a "Lock" option on the properties bar that allowed you (in sheet view) to lock the display so that when you panned and zoomed it moved the entire sheet, and when unlocked it it allowed you to pan and scale the model that was displayed on the sheet.

I upgraded to Draftsight 2017, and I can't find that option any more. All of my existing DWG files are now locked so that I cannot pan or scale existing sheets. I can only do this for new sheets that are create unlocked.

What's changed, and what am I doing wrong?