I am sorry. Just can't resist. I just don't see that big of a problem. I am not sure why the "Close Chart" is there, but I wouldn't consider it a bug, I would consider it something to never click on. But, it does what it says. It closes the chart. If you click on the red x, you get an option box, if you click on Save Chart under File (which I would never go to), you get an option.
Recent editions of Word have autosave that save rather quickly, but you can still click on the red x and choose not to save. So you can lose your Word Document as well.Choosing the diskette or Save As give you choices to save, but they are equivalent to CTRL - S or Forward Chart.
CTRL - S while getting the chart to your inbox is not as helpful as forwarding the chart with the button, because when you use that method, you can include a message as to why you are saving the chart and not signing it off. You may write waiting until CBC back. The cool thing is that whether you delete the message that was there before such as the HPI or leave it, when you pull the chart again, it reverts back to the HPI and your message disappears. I think that is rather ingenius.
I guess I am just missing what the problem is. Once the chart is open, you can either sign it off or forward/CTRL - S to inbox. The only way to lose it would be to hit the red x and choose Yes, or use the Close Chart option (which is pretty easy to avoid once you know it is there). It even saves the note if AC crashes and it's hard to blame any program for that.