This happens to me too, but only if I let the computer sit for too long without doing any activity on it. I tend to leave my computer for a few hours while I let my computer sit on the canvas... once the screen goes into hibernation mode from me not at my computer, the entire screen goes white once I come back to my drawing. I've learned my lesson and I save my drawing to my computer after each hour of work and directly before I leave the computer.

Tried a drawing today, first in Canvas draw--Half way thru, it would not show my work.  Saved it to my computer and it revealed missing scribbles , but I cannot view my work while it is being drawn.  Restarted in Java, and as I was doing the final round of touches, the screen suddenly went white and no matter what I did, I could not recover my drawing...This represents about 7 hours of work.  If these are automatically saved every 5 minutes, shuldn't it be saved somewhere?